d & f – block – JEE Main Previous Year Questions with Solutions

JEE Main Previous Year Papers Questions of Chemistry with Solutions are available at eSaral. Practicing JEE Main chapter wise questions of Chemistry will help the JEE aspirants in realizing the question pattern as well as help in analyzing weak & strong areas.

Simulator

Previous Years AIEEE/JEE Main Question

Q. In context with the transition elements, which of the following statements is incorrect?

(1) In the highest oxidation states of the first five transition elements (Sc to Mn), all the 4s

and 3d electrons are used for bonding.

(2) Once the d5 configuration is exceeded, the tendency to involve all the 3d electrons in

bonding decreases.

(3) In addition to the normal oxidation states, the zero oxidation state is also shown by these

elements in complexes.

(4) In the highest oxidation states, the transition metal show basic character and form cationic

complexes.

[AIEEE-2009]

Sol. (4)

Q. Iron exhibits +2 and +3 oxidation states. Which of the following statements about iron is

incorrect ?

(1) Ferrous compounds are more easily hydrolysed than the corresponding ferric compounds.

(2) Ferrous oxide is more basic in nature than the ferric oxide.

(3) Ferrous compounds are relatively more ionic than the corresponding ferric compounds.

(4) Ferrous compounds are less volatile than the corresponding ferric compounds.

[AIEEE-2012]

Sol. (1)

Q. Consider the following reaction : $\mathrm{xMnO}_{4}^{-}+\mathrm{yC}_{2} \mathrm{O}_{4}^{2-}+\mathrm{zH}^{+} \rightarrow \mathrm{xMn}^{2+}+2 \mathrm{yCO}_{2}+\frac{\mathrm{Z}}{2} \mathrm{H}_{2} \mathrm{O}$

The values of x, y and z in the reaction are respectively :-

(1) 5,2 and 16

(2) 2,5 and 8

(3) 2, 5 and 16

(4) 5,2 and 8

[JEE MAIN-2013]

Sol. (3)

Q. Which of the following arrangements does not represent the correct order of the property stated against it ?

(1) $\mathrm{V}^{2+}<\mathrm{Cr}^{2+}<\mathrm{Mn}^{2}<\mathrm{Fe}^{2+}$: paramagnetic behaviour

(2) $\mathrm{Ni}^{2+}<\mathrm{Co}^{2+}<\mathrm{Fe}^{2+}<\mathrm{Mn}^{2+}$: ionic size

(3)$\mathrm{Co}^{3+}<\mathrm{Fe}^{3+}<\mathrm{Cr}^{3+}<\mathrm{Sc}^{3+}$: stability in aqueous solution

(4) $\mathrm{Sc}<\mathrm{Ti}<\mathrm{Cr}<$Mn : number of oxidation states

[JEE MAIN-2013]

Sol. (1)

Q. Potassium dichromate when heated with concentrated sulphuric acid and a soluble chloride, gives brown – red vapours of:

(1) $\mathrm{CrO}_{3}$

(2) $\mathrm{Cr}_{2} \mathrm{O}_{3}$

(3) $\mathrm{CrCl}_{3}$

(4) $\mathrm{CrO}_{2} \mathrm{Cl}_{2}$

[JEE MAIN-2013, Online]

Sol. (4)

Explanation. $\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}+6 \mathrm{H}_{2} \mathrm{SO}_{4}+4 \mathrm{NaCl} \longrightarrow 2 \mathrm{KHSO}_{4}+4 \mathrm{NaHSO}_{4}+2 \mathrm{CrO}_{2} \mathrm{Cl}_{2}+3 \mathrm{H}_{2} \mathrm{O}$

Q. The element with which of the following outer electron configuration may exhibit the largest number of oxidation states in its compounds :

(1) $3 \mathrm{d}^{7} 4 \mathrm{s}^{2}$

(2) $3 \mathrm{d}^{8} 4 \mathrm{s}^{2}$

( 3) (3) $3 \mathrm{d}^{5} 4 \mathrm{s}^{2}$

(4) (4) $3 \mathrm{d}^{6} 4 \mathrm{S}^{2}$

[JEE MAIN-2013, Online]

Sol. (3)

Explanation

$\mathrm{Mn} \longrightarrow \mathrm{Mn}^{+7}$

Q. When a small amount of $\mathrm{KMnO}_{4}$ is added to concentrated $\mathrm{H}_{2} \mathrm{SO}_{4}$a green oily compound is obtained which is highly explosive in nature. Compound may be:

(1) $\mathrm{Mn}_{2} \mathrm{O}_{3}$

(2) MnSO $_{4}$

(3) $\mathrm{Mn}_{2} \mathrm{O}_{7}$

( 4) $\mathrm{MnO}_{2}$

[JEE MAIN-2013, Online]

Sol. (3)

Explanation

Q. Which series of reactions correctly represents chemical relations related to iron and its compound?

[JEE MAIN-2014]

Sol. (2)

Q. The equation which is balanced and represents the correct product (s) is:

[JEE MAIN-2014]

Sol. (4)

Q. Which of the following is not formed when $\mathrm{H}_{2} \mathrm{S}$ reacts with acidic $\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$solution ?

( 1) $\mathrm{K}_{2} \mathrm{SO}_{4}$

(2) $\mathrm{Cr}_{2}\left(\mathrm{SO}_{4}\right)_{3}$

(3) $\mathrm{S}$

(4) $\mathrm{CrSO}_{4}$

[JEE MAIN-2014, Online]

Sol. (4)

Q. Copper becomes green when exposed to moist air for a long period. This is due to :-

(1) the formation of a layer of cupric oxide on the surface of copper.

(2) the formation of basic copper sulphate layer on the surface of the metal

(3) the formation of a layer of cupric hydroxide on the surface of copper.

(4) the formation of a layer of basic carbonate of copper on the surface of copper.

[JEE MAIN-2014, Online]

Sol. (4)

Q. Which one of the following exhibits the largest number of oxidation states ?

(1) Mn(25)

(2) V(23)

(3) Cr (24)

(4) Ti (22)

[JEE MAIN-2014, Online]

Sol. (1)

Q. How many electrons are involved in the following redox reaction?

$\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}+\mathrm{Fe}^{2+}+\mathrm{C}_{2} \mathrm{O}_{4}^{2-} \rightarrow \mathrm{Cr}^{3+}+\mathrm{Fe}^{3+}+\mathrm{CO}_{2}$ (Unbalanced)

(1) 3

(2) 4

(3) 5

(4) 6

[JEE MAINS-2014,Online]

Sol. (4)

Q. Amongst the following, identify the species with an atom in +6 oxidation state:

(1) $\left[\mathrm{MnO}_{4}\right]^{-}$

(2) $\left[\mathrm{Cr}(\mathrm{CN})_{6}\right]^{3-}$

(3) $\mathrm{Cr}_{2} \mathrm{O}_{3}$

(4) $\mathrm{CrO}_{2} \mathrm{Cl}_{2}$

[JEE MAIN-2014, Online]

Sol. (4)

Q. Match the catalysts to the correct processes :-

(1) A-ii, B-iii, C-iv, D-i

(2) A-iii, B-i, C-ii, D-iv

(3) A-iii, B-ii, C-iv, D-i

(4) A-ii, B-i, C-iv, D-iii

[JEE MAIN-2015]

Sol. (4)

Q. Which of the following statements is false :-

(1) has a Cr – O – Cr bond

(2) is tetrahedral in shape

(3) $\mathrm{Na}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$ is a primary standard in volumetry

(4) $\mathrm{Na}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$ is less soluble than $\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$

[JEE MAIN-2015, Online]

Sol. (3)

Polymer – JEE Main Previous Year Questions with Solutions

JEE Main Previous Year Papers Questions of Chemistry with Solutions are available at eSaral. Practicing JEE Main chapter wise questions of Chemistry will help the JEE aspirants in realizing the question pattern as well as help in analyzing weak & strong areas.

Simulator

Previous Years AIEEE/JEE Main Questions

Q. Buna–N synthetic rubber is a copolymer of :-

[AIEEE-2009]

Sol. (1)

Buna-N is actually abbrebiated form, where Bu represents 1, 3-butadiene, Na represents

sodium and N represents nitrile (acrylonitrile).

Thus, Buna-N is a copolymer of 1, 3-butadiene and acrylonitrile usually copolymer of

1, 3-butadiene, and acrylonitrile usually ploymerise in the presence of sodium.

Q. The polymer containing strong intermolecular forces e.g. hydrogen bonding, is :-

(1) natural rubber

(2) teflon

(3) nylon 6, 6

(4) polystyrene

[AIEEE-2010]

Sol. (3)

Q. Thermosetting polymer, Bakelite is formed by the reaction of phenol with :-

(1) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CHO}$

(2) $\mathrm{CH}_{3} \mathrm{CHO}$

(3) HCHO

(4) HCOOH

[AIEEE-2011]

Sol. (3)

Bakelite is a thermosetting polymer formed by the condensation reaction of phenol with

HCHO in the presense of conc. $\mathrm{H}_{2} \mathrm{SO}_{4}$

It is thus, a cross-linked polymer in which condesation takes place at O- and p- positions

So HCHO is the corerect option.

Q. The species which can best serve as an initiator for the cationic polymerization is :-

(1) BuLi

(3) HNO $_{3}$

(4) $\mathrm{AlCl}_{3}$

[AIEEE-2012]

Sol. (4)

Electron – deficient species (Lawis acid) like $\mathrm{AlCl}_{3}, \mathrm{BF}_{3}$ etc.

are is used as initiator for cationic polymerisation.

Q. Which one is classified as a condensation polymer?

(1) Teflon

(2) Acrylonitrile

(3) Dacron

(4) Neoprene

[JEE-Main 2014]

Sol. (3)

Q. Which one of the following structures represents the neoprene polymer :-

[JEE-Main(Online) – 2015]

Sol. (3)

Q. Which polymer is used in the manufacture of paints and lacquers ?

(1) Polypropene

(2) Poly vinyl chloride

(3) Bakelite

(4) Glyptal

[JEE- Main – 2015]

Sol. (4)

Q. Which of the following statements about low density polythene is FALSE ?

(1) It is used in the manufacture of buckets, dust-bins etc.

(2) Its synthesis requires high pressure

(3) It is a poor conductor of electricity

(4) Its synthesis requires dioxygen or a peroxide initiator as a catalyst.

[JEE Main 2016]

Sol. (1)

Low density polythene : It is obtained by the polymerisation of ethene under high presure of 1000-2000 atm. at a temp. of 350 K to 570 K in the pressure of traces of dioxygen or a peroxide

Q. Assertion : Rayon is a semisynthetic polymer whose properties are better than

natural cotton.

Reason : Mechanical and aesthetic properties of cellulose can be improved by acetylation.

(1) Both assertion and reason are incorrect

(2) Assertion is incorrect statement, but the reason is correct

(3) Both assertion and reason are correct, but the reason is not the correct explanation for the

assertion

(4) Both assertion and reason are correct, and the reason is the correct explanation for the assertion

[JEE Main (Online) 2016]

Sol. (4)

Q. Which of the following polymers is synthesized using a free radical polymerization

technique ?

(1) Terylene

(2) Teflon

(3) Nylon 6,6

(4) Melamine polymer

[JEE Main (Online) 2016]

Sol. (2)

[esquestion] The formation of which of the following polymers involves hydrolysis reaction ?

(1) Nylon 6

(2) Bakelite

(3) Nylon 6, 6

(4) Terylene

#tag# [JEE – Main 2017]

Chemistry in Everyday Life – JEE Main Previous Year Questions with Solutions

JEE Main Previous Year Papers Questions of Chemistry with Solutions are available at eSaral. Practicing JEE Mains chapter wise questions of Chemistry will help the JEE aspirants in realizing the question pattern as well as help in analyzing weak & strong areas.

Simulator

Previous Years AIEEE/JEE Mains Questions

Q. Which artificial sweetener contains chlorine ?

(1) Aspartame

(2) Saccharin

(3) Sucralose

(4) Alitame

[JEE-Main(Online) – 2015]

Sol. (3)

Q. Thiol group is present in :-

(1)Methionine

(2) Cytosine

(3) Cystine

(4) Cysteine

[JEE-Main-2016]

Sol. (4)

Among 20 naturally occuring amino acids “Cysteine” has ‘– SH’ or thiol functional group.

Q. The distillation technique most suited for separating glycerol from spent-lye in the soap industry is:

(1) Distillation under reduced pressure

(2) Simple distillation

(3) Fractional distillation

(4) Steam distillation

(Jee-Main-2016)

Sol. (1)

(1) Distillation under reduced pressure.

Glycerol $\left(\mathrm{B} . \mathrm{P} .290^{\circ} \mathrm{C}\right)$ is separated from spent lye in the soap industry by distillation under reduced pressure, as for simple distillation very high temperature is required which might decompose the component.

Q. The predominant form of histamine present in human blood is $\left(\mathrm{pK}_{\mathrm{a}}\right.$, Histidine = 6.0)

(1)

(2)

(3)

(4)

Sol. (3)

Carboxylic Acid – JEE Main Previous Year Questions with Solutions

JEE Main Previous Year Papers Questions of Chemistry with Solutions are available at eSaral. Practicing JEE Mains chapter wise questions of Chemistry will help the JEE aspirants in realizing the question pattern as well as help in analyzing weak & strong areas.

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Previous Years AIEEE/JEE Mains Questions

Q. In the chemical reactions,

(1) Nitrobenzene and chlorobenzene

(2) Nitrobenzene and fluorobenzene

(3) Phenol and benzene

(4) Benzene diazonium chloride and fluorobenzene

[AIEEE-2010]

Sol. (4)

Q. In the chemical reactions

(1) Fluorobenzene and phenol

(2)Benzene diazonium chloride and benzonitrile

(3) Nitrobenzene and chlorobenzene

(4) Phenol and bromobenzene

[AIEEE-2011]

Sol. (2)

Q. Compound (A), $\mathrm{C}_{8} \mathrm{H}_{9} \mathrm{Br}$, gives a white precipitate when warmed with alcoholic $\mathrm{AgNO}_{3}$. Oxidation of (A) gives an acid (B), $\mathrm{C}_{8} \mathrm{H}_{6} \mathrm{O}_{4}$. (B) easily forms anhydride on heating. Identify the compound (A):

[AIEEE-2013]

Sol. (4)

since B on heating gives anhydride so B is 1,2 dicarboxylic acid. It contains two Benzylic carbon at 1,2 position so on oxidation it produces 1, 2-dicarboxylic acid

Q. An organic compound A upon reacting with $\mathrm{NH}_{3}$ gives B. On heating, B gives C. C in presence of KOH reacts with $\mathbf{B} \mathbf{r}_{2}$ to give $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{NH}_{2}$. A is :-

(1) $\mathrm{CH}_{3} \mathrm{COOH}$

(2) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{COOH}$

(4) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{COOH}$

[AIEEE-2013]

Sol. (4)

Q. On heating an aliphatic primary amine with chloroform & ethenolic potassium hydroside the organic compound formed is

(1) An alkyl cyanide

(2) An alkyl isocyanide

(3) an alkanol

(4) an alkanediol

[AIEEE-2014]

Sol. (2)

It is a carbyl amine reaction used for identification of primary amine also known as isocynide test because of offensive smell of isocynide.

Q. In the reaction

(1) Ethylene

(2) Acetyl chloride

(3) Acetaldehyde

(4) Acetylene.

[AIEEE-2014]

Sol. (1)

Q. In the presence of a small amount of phosphorous, aliphatic carboxylic acids react with chlorine or bromine to yield a compound in which  – hydrogen has been replaced by halogen. This reaction is known as :

(1) Etard reaction

(2) Hell – Volhard – Zelinsky reaction

(3) Wolff – Kischner reaction

(4) Rosenmund reaction

[JEE(Main)-2015]

Sol. (2)

Q. In the Hofmann bromamide degradation reaction, the number of moles of NaOH and $\mathrm{Br}_{2}$ used per mole of amine produced are :

[JEE(Main)-2016]

Sol. (1)

Q. The major product obtained in the following reaction is :-

[JEE – Main 2017]

Sol. (1)

DIBAL – H is electrophilic reducing agent reduces cynide, esters, lactone, amide, carboxylic acid into corresponding Aldehyde (partial reduction)

Q. Sodium salt of an organic acid ‘X’ produces effervescence with conc. $\mathrm{H}_{2} \mathrm{SO}_{4}$. ‘X’ reacts with the acidified aqueous CaCl2 solution to give a white precipitate which decolourises acidic solution of $\mathrm{KMnO}_{4}$. ‘X’ is :-

(1) $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{COONa}$

(2) HCOONa

(3) CH3COONa

(4) $\mathrm{Na}_{2} \mathrm{C}_{2} \mathrm{O}_{4}$

[JEE – Main – 2017]

Sol. (4)

Q. Which of the following compounds will be suitable for Kjeldahl’s method for nitrogen estimation ?

[JEE(Main)-2018]

Sol. (1)

Kjeldahl’s is suitable for Aniline. This method is used for quantitative analysis of N compound in organic substance $\left(\mathrm{NH}_{3} / \mathrm{NH}_{4}^{+}\right) .$

Carbonyl Compounds – JEE Main Previous Year Questions with Solutions

JEE Main Previous Year Papers Questions of Chemistry with Solutions are available at eSaral. Practicing JEE Mains chapter wise questions of Chemistry will help the JEE aspirants in realizing the question pattern as well as help in analyzing weak & strong areas.

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Previous Years AIEEE/JEE Mains Questions

Q. Which of the following on heating with aqueous KOH, produces acetaldehyde ?

(1) $\mathrm{CH}_{2} \mathrm{ClCH}_{2} \mathrm{Cl}$

(2) $\mathrm{CH}_{3} \mathrm{CHCl}_{2}$

(3) $\mathrm{CH}_{3} \mathrm{COCl}$

(4) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{Cl}$

[AIEEE-2009]

Sol. (2)

Q. In Cannizzaro reaction given below :-

$2 \mathrm{Ph} \mathrm{CHO}$ $\mathrm{PhCH}_{2} \mathrm{OH}+\mathrm{PhCO}_{2}^{\Theta}$ the slowest step is :-

(1) The abstraction of proton from the carboxylic group

(2) The deprotonation of $\mathrm{CH}_{2} \mathrm{OH}$

(3) The attack of $: \stackrel{\ominus}{\mathrm{O}} \mathrm{H}$ at the carboxyl group

(4) The transfer of hydride to the carbonyl group

[AIEEE-2009]

Sol. (4)

Q. One mole of a symmetrical alkene on ozonolysis gives two moles of an aldehyde having a molecular mass of 44 u. The alkene is :-

(1) Ethene (2) Propene (3) 1-Butene (4) 2-Butene

[AIEEE-2010]

Sol. (4)

Q. Ozonolysis of an organic compound gives formaldehyde as one of the products. This confirms the presence of :-

(1) An isopropyl group

(2) An acetylenic triple bond

(3) Two ethylenic double bonds

(4) A vinyl group

[AIEEE-2011]

Sol. (4)

Q. Ozonolysis of an organic compound ‘A’ produces acetone and propionaldehyde in equimolar mixture. Identify ‘A’ from the following compounds : –

(1) 2-Methyl – 1- pentene

(2) 1-Pentene

(3) 2-Pentene

(4) 2-Methyl-2-pentene

[AIEEE-2011]

Sol. (4)

Q. Trichloroacetaldehyde was subjected to Cannizzaro’s reaction by using NaOH. The mixture of the products contains sodium trichloroacetate and another compound. The other

(1) 2,2,2–Trichloropropanol

(2) Chloroform

(3) 2,2,2–Trichloroethanol

(4) Trichloromethanol

[AIEEE-2011]

Sol. (3)

Q. Silver Mirror test is given by which one of the following compounds?

(1) Formaldehyde (2) Benzophenone (3) Acetaldehyde (4) Acetone

[AIEEE-2011]

Sol. (1,3)

Q. In the given transformation, which of the following is the most appropriate reagent ?

(1) $\mathrm{NaBH}_{4}$

(2) $\mathrm{NH}_{2} \mathrm{NH}_{2}, \stackrel{\ominus}{\mathrm{O}} \mathrm{H}$

(3) Zn – Hg / HCl

$(4) \mathrm{Na}, \mathrm{Liq.NH}_{3}$

[AIEEE-2012]

Sol. (2)

Q. Iodoform can be prepared from all except :-

(1) Isobutyl alcohol

(2) Ethyl methyl ketone

(3) Isopropyl alcohol

(4) 3-Methyl–2–butanone

[AIEEE-2012]

Sol. (1)

Q. A compound with molecular mass 180 is acylated with $\mathrm{CH}_{3} \mathrm{COCl}$ to get a compound with molecular mass 390. The number of amino groups present per molecule of the former compound is :-

(1) 2 (2) 5 (3) 4 (4) 6

[JEE(Main)-2013]

Sol. (2)

180 molecular mass after acylation gives compound of molecular mass 390.

Change in molecular mass = 390 – 180 = 210

so number of $\mathrm{NH}_{2}$= $\frac{210}{42}$ = 5 group

Q. The major organic compound formed by the reaction of 1, 1, 1–trichloroethane with silver powder is :-

(1)2-Butyne

(2) 2-Butene

(3) Acetylen

(4) Ethene

[JEE(Main)-2014]

Sol. (1)

Q. The most suitable reagent for the conversion of $\mathrm{R}-\mathrm{CH}_{2}-\mathrm{OH} \rightarrow \mathrm{R}-\mathrm{CHO}$ is :-

(1) $\mathrm{CrO}_{3}$

(2) PCC (Pyridinium chlorochromate)

(3) $\mathrm{KMNO}_{4}$

(4) $\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$

[JEE(Main)-2014]

Sol. (2)

PCC is milder oxidising agent, oxidises only into aldehyde.

Q. A compound A with molecular formula $\mathrm{C}_{10} \mathrm{H}_{13} \mathrm{Cl}$ gives a white precipitate on adding silver nitrate solution. A on reacting with alcoholic KOH gives compound B as the main product. B on ozonolysis gives C and D. C gives Cannizaro reaction but not aldol condensation. D gives aldol condensation but not Cannizaro reaction. A is :

#tag [JEE(Main)-2015]

Sol. (2)

Q. In the reaction sequence

; the product B is:-

(1) $\mathrm{CH}_{3}-\mathrm{CH}=\mathrm{CH}-\mathrm{CHO}$

(2) $\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{CH}_{3}$

(3) $\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{OH}$

(4)

[JEE(Main)-2015]

Sol. (1)

Q. Which compound would give 5-keto-2-methyl hexanal upon ozonlysis?

[JEE(Main) 2015]

Sol. (4)

Biomolecule – JEE Main Previous Year Questions with Solutions

JEE Main Previous Year Papers Questions of Chemistry with Solutions are available at eSaral. Practicing JEE Mains chapter wise questions of Chemistry will help the JEE aspirants in realizing the question pattern as well as help in analyzing weak & strong areas.

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Previous Years AIEEE/JEE Main Questions

Q. The two functional groups present in a typical carbohydrate are :-

(1) >C = O and –OH (2) –OH and –CHO (3) –OH and –COOH (4) –CHO and –COOH

AIEEE-2009

Sol. (2)

Q. Biurest test is not given by :-

(1) proteins (2) carbohydrates (3) polypeptides (4) urea

AIEEE-2010

Sol. (2)

Q. The presence or absence of hydroxy group on which carbon atom of sugar differentiates RNA and DNA?

(1) 3rd (2) 4th (3) 1st (4) 2nd

AIEEE-2011

Sol. (4)

Q. The change in the optical rotation of freshly prepared solution of glucose is known as :-

(1) tautomerism (2) racemisation (3) specific rotation (4) mutarotation

AIEEE-2011

Sol. (4)

Q. Which one of the following statements is correct ?

(1) All amino acids except glutamic acid are optically active

(2) All amino acids except lysine are optically active

(3) All amino acids are optically active

(4) All amino acids except glycine are optically active

AIEEE-2012

Sol. (4)

Q. Synthesis of each molecule of glucose in photosynthesis involves :-

(1) 18 molecules of ATP

(2) 10 molecules of ATP

(3) 8 molecules of ATP

(4) 6 molecules of ATP

JEE Main -2013

Sol. (1)

Six rounds of the Calvin cycle are required, because one carbon atom is reduced in each round. Twelve molecules of ATP are expended. An additional six molecular of ATP are spent in regenerating ribulose-1, 5-biphosphate

$6 \mathrm{CO}_{2}+18 \mathrm{ATP}+12 \mathrm{NADPH}+12 \mathrm{H}_{2} \mathrm{O} \rightarrow$

$\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}+18 \mathrm{ADP}+18 \mathrm{P}_{\mathrm{i}}+12 \mathrm{NADP}+6 \mathrm{H} \oplus$

Reference : NCERT 11th class chapter-13 (Photosynthesis Pg. 217, 218 in higher plants.

Calvin cycle where sugar is synthesised is as follows :

The Calvin cycle proceeds in three stages (1) carboxylation, during which $\mathrm{CO}_{2}$ combines with ribulose-1.5-bisphosphate (2) reduction, during which carbohydrate is formed at the expense of the photochemically made ATP and NADPH and (3) regeneration during which the $\mathrm{CO}_{2}$ acceptor ribulose-1,5-bisphosphate is formed again so that the cylcle continues.

It might help you to understand all of this if we look at what goes in and what comes out of the Calvin cycle.

Q. Which one of the following bases is not present in DNA ?

(1) Cytosine (2) Thymine (3) Quinoline (4) Adenine

JEE-Main 2014

Sol. (3)

All cytosine, thymine and adenine are present in DNA. Only quinoline is not present in DNA.

Q. Which of the vitamins given below is water soluble?

(1) Vitamin E

(2) Vitamin K

(3) Vitamin C

(4) Vitamin D

JEE-Main 2015

Sol. (3)

Vitamine C is soluble in water due to H-Bonding & all other vitamines given in question are fat soluble.

Q. Complete hydrolysis of starch gives :

(1) glucose and fructose in equimolar amounts

(2) glucose only

(3) galactose and fructose in equimolar amounts

(4) glucose and galactose in equimolar amounts

JEE-Main(Online) – 2015

Sol. (2)

Starch is polymer of Glucose

Q. Accumulation of which of the following molecules in the muscles occurs as a result of vigorous exercise :-

(1) Pyruvic acid

(2) L-lactic acid

(3) Glycogen

(4) Glucose

JEE-Main(Online) – 2015

Sol. (2)

Q. Consider the following sequence for aspartic acid:

The pI (isoelectric point) of aspartic acid is :

(1) 1.88 (2) 2.77 (3) 3.65 (4) 5.74

JEE-Main(Online) – 2016

Sol. (4)

Q. Observation of “Rhumann’s purple” is a confirmatory test for the presence of :

(1) Starch

(2) Reducing sugar

(3) Cupric ion

(4) Protein

JEE-Main(Online) – 2017

Sol. (1)

Q. Which of the following compounds will behave as a reducing sugar in an aqueous KOH solution ?

JEE-Main 2017

Sol. (1)

(1) Ester in presence of Aqueous KOH solution give SNAE reaction so following reaction takes place

Alcohol & Ether – JEE Main Previous Year Questions with Solutions

JEE Main Previous Year Papers Questions of Chemistry with Solutions are available at eSaral. Practicing JEE Mains chapter wise questions of Chemistry will help the JEE aspirants in realizing the question pattern as well as help in analyzing weak & strong areas.

Simulator

Previous Years AIEEE/JEE Mains Questions

Q. The number of stereoisomers possible for a compound of the molecular formula

(1) 4        (2) 6         (3) 3           (4) 2

AIEEE-2009

Sol. (1)

Q. A liquid was mixed with ethanol and a drop of concentrated $\mathrm{H}_{2} \mathrm{SO}_{4}$ was added. A compound with a fruity smell was formed. The liquid was :-

(1) $\mathrm{CH}_{3} \mathrm{COCH}_{3}$

(2) $\mathrm{CH}_{3} \mathrm{COOH}$

(3) $\mathrm{CH}_{3} \mathrm{OH}$

(4) HCHO

AIEEE-2009

Sol. (2)

Q. From amongst the following alcohols the one that would react fastest with conc. HCl and anhydrous $\mathrm{ZnCl}_{2}$, is :-

(1) 1–Butanol

(2) 2–Butanol

(3) 2–Methylpropan–2–ol

(4) 2–Methylpropanol

AIEEE-2010

Sol. (3)

Q. Consider the following reaction :

$\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}+\mathrm{H}_{2} \mathrm{SO}_{4} \rightarrow$ Produce

Among the following, which one cannot be formed as a product under any conditions ?

(1) Ethyl-hydrogen sulphate

(2) Ethylene

(3) Acetylene

(3) Diethyl ethe

AIEEE-2011

Sol. (3)

Q. Iodoform can be prepared from all except :-

(1) Isobutyl alcohol

(2) Ethyl methyl ketone

(3) Isopropyl alcohol

(4) 3-Methyl–2–butanone

AIEEE-2012

Sol. (1)

Q. An unknown alcohol is treated with the “Lucas reagent’ to determine whether the alcohol is primary, secondary or tertiary. Which alcohol reacts fastest and by what mechanism :-

(1) secondary alcoholby SN $^{1}$

(2) tertiary alcohol by SN $^{1}$

(3) secondary alcoholby SN $^{2}$

(4) tertiary alcohol by SN $^{2}$

AIEEE-2013

Sol. (2)

Q. The most suitable reagent for the conversion of $\mathrm{R}-\mathrm{CH}_{2}-\mathrm{OH} \rightarrow \mathrm{R}-\mathrm{CHO}$ is :

(1) $\mathrm{CiO}_{3}$

(2) PCC (Pyridinium chlorochromate)

(3) KMNO $_{4}$

(4) $\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$

Jee-Main-2014

Sol. (2)

Q. Allyl phenyl ether can be prepared by heating:

(1) $\mathrm{CH}_{2}=\mathrm{CH}-\mathrm{CH}_{2}-\mathrm{Br}+\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{ONa}$

(2) $\mathrm{C}_{6} \mathrm{H}_{5}-\mathrm{CH}=\mathrm{CH}-\mathrm{Br}+\mathrm{CH}_{3}-\mathrm{ONa}$

(3) $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{Br}+\mathrm{CH}_{2}=\mathrm{CH}-\mathrm{CH}_{2}-\mathrm{ONa}$

(4) $\mathrm{CH}_{2}=\mathrm{CH}-\mathrm{Br}+\mathrm{C}_{6} \mathrm{H}_{5}-\mathrm{CH}_{2}-\mathrm{ONa}$

Jee-Main-2014

Sol. (1)

Q. In the Victor-Meyer’s test, the colour given by $1^{\circ}, 2^{\circ}$ and $3^{\circ}$ alcohols are respectively :-

(1) Red, blue, colourless

(2) Colourless, red, blue

(3) Red, blue, violet

(4) Red, colourless, blue

Jee-Main-2014

Sol. (1)

Q. Williamson synthesis of ether is an example of

(2) Electrophilic substitution

(3) Nucleophilic substitution

Jee-Main-2014

Sol. (3)

Nucleophilic substitution

Q. Phenol on treatment with $\mathrm{CO}_{2}$ in the presence of NaOH followed by acidification produces compound X as the major product. X on treatment with $\left(\mathrm{CH}_{3} \mathrm{CO}\right)_{2} \mathrm{O}$ in the presence of catalytic amount of $\mathrm{H}_{2} \mathrm{SO}_{4}$ produces :

Jee-Main-2018

Sol. (4)

Q. Phenol reacts with methyl chloroformate in the presence of NaOH to form product A. A reacts with $\mathrm{Br}_{2}$ to form product B. A and B are respectively :

Jee-Main-2018

Sol. (2)

Salt Analysis – JEE Main Previous Year Questions with Solutions

JEE Main Previous Year Papers Questions of Chemistry with Solutions are available at eSaral. Practicing JEE Main chapter wise questions of Chemistry will help the JEE aspirants in realising the question pattern as well as help in analysing weak & strong areas.

Simulator

Previous Years AIEEE/JEE Mains Questions

Q. The products obtained on heating LiNO3 will be :-

(1) $\mathrm{LiNO}_{2}+\mathrm{O}_{2}$

(2) $\mathrm{Li}_{2} \mathrm{O}+\mathrm{NO}_{2}+\mathrm{O}_{2}$

(3) $\mathrm{Li}_{3} \mathrm{N}+\mathrm{O}_{2}$

(4) $\mathrm{Li}_{2} \mathrm{O}+\mathrm{NO}+\mathrm{O}_{2}$

AIEEE-2011

Sol. (2)

$\mathrm{LiNO}_{3} \longrightarrow \mathrm{Li}_{2} \mathrm{O}+\mathrm{NO}_{2}+\mathrm{O}$

Q. What is the best description of the change that occurs when $\mathrm{Na}_{2} \mathrm{O}(\mathrm{s})$ is dissolved in water ?

(1) Oxidation number of sodium decreases

(2) Oxide ion accepts sharing in a pair of electrons

(3) Oxide ion donates a pair of electrons

(4) Oxidation number of oxygen increases

AIEEE-2011

Sol. (3)

$\mathrm{Na}_{2} \mathrm{O}+\mathrm{HOH} \longrightarrow \mathrm{CaO}+\mathrm{CO}_{2}$

Q. Which of the following on thermal-decomposition yields a basic as well as an acidi oxide ?

(1) $\mathrm{NH}_{4} \mathrm{NO}_{3}$

(2) NaNO $_{3}$

(3) $\mathrm{KClO}_{3}$

(4) $\mathrm{CaCO}_{3}$

AIEEE-2012

Sol. (4)

$\mathrm{CaCO}_{3} \longrightarrow \mathrm{CaO}+\mathrm{CO}_{2}$

Q. Fire extinguishers contain H2SO4 and which one of the following :-

(1) $\mathrm{CaCO}_{3}$

(2) $\mathrm{NaHCO}_{3}$ and $\mathrm{Na}_{2} \mathrm{CO}_{3}$

(3) $\mathrm{Na}_{2} \mathrm{CO}_{3}$

(4) $\mathrm{NaHCO}_{3}$

JEE(Main)-2012 online-P-1

Sol. (4)

Fire extinguishers contain H2SO4 and NaHCO3

Q. Copper wire test for halogens is known as :-

(1) Duma’s Test

(2) Beilstein’s Test

(3) Lasssigne’s Test

(4) Liebig’s Test

JEE(Main)-2012 online-P-2

Sol. (2)

Beilstein’s Test

Q. The standard potentials of $\mathrm{Ag}^{+} / \mathrm{Ag}, \mathrm{Hg}_{2}^{2+} / 2 \mathrm{Hg}, \mathrm{Cu}^{2+} / \mathrm{Cu}$ and $\mathrm{Mg}^{2+} /$ Mg electrodes are 0.80, 0.79, 0.34 and – 2.37 V, respectively. An aqueous solution which contains one mole per litre of the salts of each of the four metals is electrolyzed. With increasing voltage, the correct sequence of deposition of the metals at the cathode is :-

(1) Cu, Hg, Ag only

(2) Mg, Cu, Hg, Ag

(3) Ag, Hg, Cu only

(4) Ag, Hg, Cu, Mg

[JEE(Main)-2012 online-P-3]

Sol. (3)

Q. Beilstein test is used for estimation of which one of following elements ?

(1) S

(2) Cl

(3) C and H

(4) N

JEE(Main)-2012 online-P-3

Sol. (2)

$5 \mathrm{Mn} \mathrm{O}_{4}^{-}+2 \mathrm{C}_{2} \mathrm{O}_{4}^{2-}+16 \mathrm{H}^{+} \longrightarrow 5 \mathrm{Mn}^{+2}+2 \mathrm{CO}_{2}+\frac{16}{2} \mathrm{H}_{2} \mathrm{O}$

Q. In the following balanced reaction, $\mathrm{XMnO}_{+}^{-}+\mathrm{YC}_{2} \mathrm{O}_{4}^{2-}+\mathrm{ZH}^{+}=\mathrm{XMn}^{2+}+2 \mathrm{YCO}_{2}+$ $\frac{\mathrm{Z}}{2} \mathrm{H}_{2} \mathrm{O}$ the values of X, Y and Z, respectively are :-

JEE(Main)-2012 online-P-4

Sol. (2)

Q. A metal M on heating in nitrogen gas gives Y. Y on treatment with $\mathrm{H}_{2} \mathrm{O}$ gives a colourless gas which when passed through $\mathrm{CuSO}_{4}$ solution gives a blue colour, Y is :-

(1) $\mathrm{NH}_{3}$

(2) MgO

(3) $\mathrm{Mg}_{3} \mathrm{N}_{2}$

(4) $\mathrm{Mg}\left(\mathrm{NO}_{3}\right)_{2}$

JEE(Main)-2012 online-P-4

Sol. (3)

Q. Electrode potentials (E0) are given below :

$\mathrm{Cu}^{+} / \mathrm{Cu}=+0.52 \mathrm{V}, \mathrm{Fe}^{3+} / \mathrm{Fe}^{2+}=+0.77 \mathrm{V}$

$1 / 2 \mathrm{I}_{2}(\mathrm{s}) / \mathrm{I}^{-}=+0.54 \mathrm{V}, \mathrm{Ag}^{+} / \mathrm{Ag}=+0.88 \mathrm{V}$

Based on the above potentials, strnogest oxidizing agent will be :

(1) $\mathrm{Cu}^{+}$

(3) $\mathrm{Ag}^{+}$

(4) $\mathrm{I}_{2}$

JEE(Main)-2013 online-P-1

Sol. (3)

Q. Potassium dichromate when heated with concentrated sulphuric acid and a soluble chloride, gives brown – red vapours of:

( 1) $\mathrm{CrO}_{3}$

(2) $\mathrm{Cr}_{2} \mathrm{O}_{3}$

(3) $\mathrm{CrCl}_{3}$

(4) $\mathrm{CrO}_{2} \mathrm{Cl}_{2}$

JEE(Main)-2013 online-P-1

Sol. (4)

Q. Given :

$\overline{\mathrm{X}} \mathrm{Na}_{2} \mathrm{HAsO}_{3}+\mathrm{Y} \mathrm{NaBrO}_{3}+\mathrm{ZHCl} \rightarrow \mathrm{NaBr}+\mathrm{H}_{3} \mathrm{AsO}_{4}+\mathrm{NaCl}$

The values of X, Y and Z in the above redox reaction are respectively :

(1) 2, 1, 3 (2) 3, 1, 6 (3) 2, 1, 2 (4) 3, 1, 4

JEE(Main)-2013 online-P-1

Sol. (2)

$3 \mathrm{Na}_{2} \mathrm{HAsO}_{3}+\mathrm{NaBrO}_{3}+6 \mathrm{HCl} \longrightarrow \mathrm{NaBr}+\mathrm{H}_{3} \mathrm{AsO}_{4}+\mathrm{NaCl}$

Q. Sodium Carbonate cannot be used in place of $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{CO}_{3}$ for the identification of $\mathrm{Ca}^{2+}, \mathrm{Ba}^{2+}$ and $\mathrm{Sr}^{2+}$ ions (in group V) during mixture analysis because :

(1) Sodium ions will react with acid radicals

(2) Concentration of $\mathrm{CO}_{3}^{2-}$ ions is very low

(3) Mg $^{2+}$ ions will also be precipitated

(4) $\mathrm{Na}^{+}$ ions will interfere with the detection of $\mathrm{Ca}^{2+}, \mathrm{Ba}^{2+}, \mathrm{Sr}^{2+}$ ions

JEE(Main)-2013 online-P-1

Sol. (3)

According to reactivity series Mg can be displaced by Na.

Q. Which of the following statements is incorrect?

(1) $\mathrm{Fe}^{2+}$ ion also gives blood red colour with $\mathrm{SCN}^{-}$ ion

(2) Cupric ion reacts with excess of ammonia solution to give deep blue colour of $\left[\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4}\right]^{2+}$ ion.

(3) $\mathrm{Fe}^{3+}$ ion gives blood red colour with $\mathrm{SCN}^{-}$ ion.

(4) On passing $\mathrm{H}_{2} \mathrm{S}$ into $\mathrm{Na}_{2} \mathrm{ZnO}_{2}$ solution, a white ppt of ZnS is formed.

Sol. (1)

$\mathrm{Fe}^{+2}+\mathrm{SCN}^{-} \longrightarrow$ No colour

Q. Values of dissociation constant, $\mathrm{K}_{\mathrm{a}}$ are given as follows :

(1) $\mathrm{NO}_{2}^{-}<\mathrm{CN}^{-}<\mathrm{F}^{-}$

(2) $\mathrm{F}^{-}<\mathrm{CN}^{-}<\mathrm{NO}_{2}^{-}$

(3) $\mathrm{NO}_{2}^{-}<\mathrm{F}^{-}<\mathrm{CN}^{-}$

(4) $\mathrm{F}^{-}<\mathrm{NO}_{2}^{-}<\mathrm{CN}^{-}$

JEE(Main)-2013 online-P-2

Sol. (4)

Order of basic strength according to Ka value.

$\mathrm{CN}^{-}>\mathrm{NO}_{2}^{-}>\mathrm{F}^{-}$

Q. Identify incorrect statement

(1) Copper (I) compounds are colourless except where colour results from charge transfer

(2) Copper (I) compounds are diamagnetic

(3) $\mathrm{Cu}_{2} \mathrm{S}$ is black

(4) $\mathrm{Cu}_{2} \mathrm{O}$ is colourless

JEE(Main)-2013 online-P-3

Sol. (4)

$\mathrm{Cu}_{2} \mathrm{O}$ is red.

Q. Given :

$\mathrm{E}_{1 / 2 \mathrm{C}_{2} / \mathrm{Cl}^{-}}^{0}=1.36 \mathrm{V}, \mathrm{E}_{\mathrm{Cr}^{3+} / \mathrm{Gr}}^{0}=-0.74 \mathrm{V} ; \quad \mathrm{E}_{\mathrm{G}_{2} \mathrm{O}_{7}^{2-} / \mathrm{Cr}^{3+}}^{0}=1.33 \mathrm{V}, \mathrm{E}_{\mathrm{MnO}_{4}^{-} / \mathrm{Mn}^{2+}}^{0}=1.51 \mathrm{V}$

The correct order of reducing power of the species $\left(\mathrm{Cr}, \mathrm{Cr}^{3+}, \mathrm{Mn}^{2+} \text { and } \mathrm{Cl}^{-}\right)$ will be :

JEE(Main)-2013 online-P-3

(1) $\mathrm{Mn}^{2+}<\mathrm{Cl}^{-}<\mathrm{Cr}^{3+}<\mathrm{Cr}$

(2) $\mathrm{Cr}^{3+}<\mathrm{Cl}^{-}<\mathrm{Mn}^{2+}<\mathrm{Cr}$

(3) $\mathrm{Cr}^{3+}<\mathrm{Cl}^{-}<\mathrm{Cr}<\mathrm{Mn}^{2+}$

(4) $\mathrm{Mn}^{2+}<\mathrm{Cr}^{3+}<\mathrm{Cl}^{-}<$

Sol. (1)

Order of reducing power acoording to E

$\mathrm{Cr}>\mathrm{Cr}^{+3}>\mathrm{Cl}^{-}>\mathrm{Mn}^{+2}$

Q. Which one of the following cannot function as an oxidising agent ?

(1) $\mathrm{NO}_{3}^{-}(\mathrm{aq})$

( 2) $\mathrm{I}^{-}$

(3) $\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}$

( 4) $\mathrm{S}_{(\mathrm{S})}$

JEE(Main)-2014 online_P-2

Sol. (2)

$\mathrm{I}^{-}$ has lowest oxidation state.

Q. Which of the following statements about $\mathrm{Na}_{2} \mathrm{O}_{2}$ is not correct ?

(1) $\mathrm{Na}_{2} \mathrm{O}_{2}$ oxidises $\mathrm{Cr}^{3+}$ to $\mathrm{CrO}_{4}^{2-}$ in acid medium

(2) It is diamagnetic in nature

(3) It is the super oxide of sodium

(4) It is a derivative of $\mathrm{H}_{2} \mathrm{O}_{2}$

JEE(Main)-2014 online_P-2

Sol. (2)

$\mathrm{Na}_{2} \mathrm{O}_{2}$ is peroxide

Q. Given :-

$\mathrm{Fe}^{3+}(\mathrm{aq})+\mathrm{e}^{-} \rightarrow \mathrm{Fe}^{2+}(\mathrm{aq}) ; \mathrm{E}^{\circ}=+0.77 \mathrm{V}$

$\mathrm{A}^{3+}(\mathrm{aq})+3 \mathrm{e}^{-} \rightarrow \mathrm{Al}(\mathrm{s}) ; \mathrm{E}^{\circ}=-1.66 \mathrm{V}$

$\mathrm{Br}_{2}(\mathrm{aq})+2 \mathrm{e}^{-} \rightarrow 2 \mathrm{Br}^{-} ; \mathrm{E}^{\circ}=+1.09 \mathrm{V}$

Considering the electrode potentials, which of the following represents the correct order of reducing power?

(1) $\mathrm{Al}<\mathrm{Fe}^{2+}<\mathrm{Br}^{-}$

(2) $\mathrm{Al}<\mathrm{Br}^{-}<\mathrm{Fe}^{2+}$

(3) $\mathrm{Fe}^{2+}<\mathrm{Al}<\mathrm{Br}^{-}$

$(4) \mathrm{Br}^{-}<\mathrm{Fe}^{2+}<\mathrm{Al}$

JEE(Main)-2014 online-P-2

Sol. (4)

Order of reducing power according to $\mathrm{E}^{\circ}$ $\mathrm{Br}^{-}<\mathrm{Fe}^{+2}<\mathrm{Al}$

Q. Consider the following equilibrium

White precipitate of AgCl appears on adding which of the following?

(1) $\mathrm{NH}_{3}$

(2) Aqueous NaCl

(3) Aqueous $\mathrm{NH}_{4} \mathrm{Cl}$

(4) AqueousHNO $_{3}$

JEE(Main)-2014 online-P-2

Sol. (4)

$\left[\mathrm{Ag}\left(\mathrm{NH}_{3}\right)_{4}\right] \mathrm{Cl}+\mathrm{aqH} \mathrm{NO}_{3} \longrightarrow \mathrm{AgCl} \downarrow$

Q. Copper becomes green when exposed to moist air for a long period. This is due to :-

(1) the formation of a layer of cupric oxide on the surface of copper.

(2) the formation of basic copper sulphate layer on the surface of the metal

(3) the formation of a layer of cupric hydroxide on the surface of copper.

(4) the formation of a layer of basic carbonate of copper on the surface of copper.

JEE(Main)-2014 online-P-3

Sol. (4)

$\mathrm{Cu} \frac{\text { Moist }}{\mathrm{air}}>\mathrm{CuCO}_{3} \cdot \mathrm{Cu}(\mathrm{OH})_{2}$

Q. The correct statement for the molecule, $\mathrm{CsI}_{3},$ is:

(1) it contains $\mathrm{Cs}^{3+}$ and $\mathrm{I}^{-}$ ions

(2) dit contains $\mathrm{Cs}^{3+}$ and $\mathrm{I}^{-}$ ions

(3) it is a covalent molecule

(4) it contains $\mathrm{Cs}^{+}$ and $\mathrm{I}_{3}^{-}$ ions

JEE(Main)-2014

Sol. (4)

$\mathrm{CsI}_{3} \longrightarrow \mathrm{Cs}^{+}+\mathrm{I}_{3}^{-}$

Q. Which one of the following exhibits the largest number of oxidation states ?

(1) Mn(25)

(2) V(23)

(3) Cr (24)

(4) Ti (22)

JEE(Main)-2014 online-P-3

Sol. (1)

Mn has maximum number of oxidation state.

Q. Hydrogen peroxide acts both as an oxidising and as a reducing agent depending upon the nature of the reacting species. In which of the following cases $\mathrm{H}_{2} \mathrm{O}_{2}$ acts as a reducing agent in acid medium ? :-

JEE(Main)-2014 online-P-3

(1) $\mathrm{MnO}_{4}^{-}$

(2) $\mathrm{SO}_{3}^{2-}$

(3) KI

(4) $\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}$

Sol. (1)

$\mathrm{H}_{2} \mathrm{O}_{2}$ acts as a reducing agent in acidic medium in pressure of $\mathrm{MnO}_{4}^{-}$

Q. Consider the reaction

$\mathrm{H}_{2} \mathrm{SO}_{3(\mathrm{aq})}+\mathrm{Sn}_{(\mathrm{aq})}^{4+}+\mathrm{H}_{2} \mathrm{O}_{(\mathrm{l})} \rightarrow \mathrm{Sn}_{(\mathrm{aq})}^{2+}+\mathrm{HSO}_{4(\mathrm{aq})}^{-}+3 \mathrm{H}_{(\mathrm{aq})}^{+}$

Which of the following statements is correct?

(1) $\mathrm{H}_{2} \mathrm{SO}_{3}$ is the reducing agent because it undergoes oxidation

(2) $\mathrm{H}_{2} \mathrm{SO}_{3}$ is the reducing agent because it undergoes reduction

(3) $\mathrm{Sn}^{4+}$ is the reducing agent because it undergoes oxidation

(4) $\mathrm{Sn}^{4+}$ is the oxidizing agent because it undergoes oxidation

JEE(Main)-2014 online-P-4

Sol. (1)

Q. How many electrons are involved in the following redox reaction ?

$\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}+\mathrm{Fe}^{2+}+\mathrm{C}_{2} \mathrm{O}_{4}^{2-} \rightarrow \mathrm{Cr}^{3+}+\mathrm{Fe}^{3+}+\mathrm{CO}_{2}$ (Unbalanced)

(1) 3 (2) 4 (3) 5 (4) 6

JEE(Main)-2014 online-P-4

Sol. (4)

$6 e^{-}$ are involved in this reaction

Q. Amongst the following, identify the species with an atom in +6 oxidation state:

(1) $\left[\mathrm{MnO}_{4}\right]^{-}$

(2) $\left[\mathrm{Cr}(\mathrm{CN})_{6}\right]^{3-}$

(3) $\mathrm{Cr}_{2} \mathrm{O}_{3}$

(4) $\mathrm{Cr} \mathrm{o}_{2} \mathrm{Cl}_{2}$

JEE(Main)-2014 online-P-4

Sol. (4)

$\mathrm{CrO}_{2} \mathrm{Cl}_{2} \mathrm{x}+(-4)+(-2)=0$

$\mathrm{x}=+6$

Q. Which of the following salts is the most basic in aqueous solution ?

( 1) $\mathrm{CH}_{3} \mathrm{COOK}$

( 2) $\mathrm{FeCl}_{3}$

(3) $\mathrm{Pb}\left(\mathrm{CH}_{3} \mathrm{COO}\right)_{2}$

(4) $\mathrm{Al}(\mathrm{CN})_{3}$

JEE(Main)-2018

Sol. (1)

Surface Chemistry – JEE Main Previous Year Questions with Solutions

JEE Main Previous Year Papers Questions of Chemistry with Solutions are available at eSaral. Practicing JEE Main chapter wise questions of Chemistry will help the JEE aspirants in realizing the question pattern as well as help in analyzing weak & strong areas.

Simulator

Previous Years AIEEE/JEE Main Questions

Q. Which of the following statements is incorrect regarding physisorptions ?

(1) Under high pressure it results into multi molecular layer on adsorbent surface

(2) Enthalpy of adsorption $\left(\Delta \mathrm{H}_{\text {adsorption }}\right)$ is low and

positive

(3) It occurs because of Van der Waal’s forces

AIEEE-2009

Sol. (2)

$\Delta \mathrm{H}$ is negative

Q. According to Freundlich adsorption isotherm, which of the following is correct ?

(1) $\frac{\mathrm{x}}{\mathrm{m}} \propto \mathrm{p}^{0}$

(2) $\frac{\mathrm{x}}{\mathrm{m}} \propto \mathrm{p}^{1}$

(3) $\frac{\mathrm{x}}{\mathrm{m}} \propto \mathrm{p}^{1 / \mathrm{n}}$

(4) All the above are correct for different ranges of pressure

AIEEE-2012

Sol. (4)

Q. The coagulating power of electrolytes having ions $\mathrm{Na}^{+}, \mathrm{Al}^{3+}$ and $\mathrm{Ba}^{2+}$ for aresenic sulphide sol increases in the order :-

(1) $\mathrm{Al}^{3+}<\mathrm{Ba}^{2+}<\mathrm{Na}^{+}$

(2) $\mathrm{Na}^{+}<\mathrm{Ba}^{2+}<\mathrm{Al}^{3+}$.

(3) $\mathrm{Ba}^{2+}<\mathrm{Na}^{+}<\mathrm{Al}^{3+}$

(4) $\mathrm{Al}^{3+}<\mathrm{Na}^{+}<\mathrm{Ba}^{2+}$

JEE-Main 2013

Sol. (2)

According to hardley schuzle rule

Q. For a linear plot of log(x/m) versus log p in a Freundlich adsorption isotherm, which of the following statements is correct ? (k and n are constants)

(1) log (1/n) appears as the intercept

(2) Both k and 1/n appear in the slope term

(3) 1/n appears as the intercept

(4) Only 1/n appears as the slope

JEE-Main 2016

Sol. (4)

According to Freundlich isotherm

Q. The Tyndall effect is observed only when following conditions are satisfied :-

(a) The diameter of the dispersed particles is much smaller than the wavelength of the ligh

used.

(b) The diameter of the dispersed particle is not much smaller than the wavelength of the light

used.

(c) The refractive indices of the dispersed phase and dispersion medium are almost similar in

magnitude.

(d) The refractive indices of the dispersed phase and dispersion medium differ greatly in

magnitude.

(1) (a) and (d)

(2) (b) and (d)

(3) (a) and (c)

(4) (b) and (c)

JEE – Main – 2017

Sol. (2)

As per NCERT book (fact)

Solid State – JEE Main Previous Year Questions with Solutions

JEE Main Previous Year Papers Questions of Chemistry with Solutions are available at eSaral. Practicing JEE Main chapter wise questions of Chemistry will help the JEE aspirants in realizing the question pattern as well as help in analyzing weak & strong areas.

Simulator

Previous Years AIEEE/JEE Mains Questions

Q. The edge length of a face centered cubic cell of an ionic substance is 508 pm. If the radius of the cation is 110 pm, the radius of the anion is :-

(1) 144 pm (2) 288 pm (3) 398 pm (4) 618 pm

Aieee-10

Sol. (1)

radius of cation = 110 pm

if cation present 2n OV

$a=2\left(r_{+}+r_{-}\right)$

508 = 2[110 + x]

x = 144 pm

Q. Percentages of free space in cubic close packed structure and in body centered packed structure are respectively :-

(1) 48% and 26% (2) 30% and 26% (3) 26% and 32% (4) 32% and 48%

Aieee-10

Sol. (3)

Theory Based

Q. Copper crystallises in fcc lattice with a unit cell edge of 361 pm. The radius of copper atom is:-

(1) 181 pm (2) 108 pm (3) 128 pm (4) 157 pm

Aieee-11 / JEE-Main-ONLINE 2013

Sol. (3)

Q. In a face centred cubic lattice, atom A occupies the corner positions and atom B occupies the face centre positions. If one atom of B is missing from one of the face centred points, the formula of the compound is :-

(1) $\mathrm{A}_{2} \mathrm{B}_{3}$

( 2) $\mathrm{A}_{2} \mathrm{B}_{5}$

(3) $\mathrm{A}_{2} \mathrm{B}$

(4) $\mathrm{AB}_{2}$

Aieee-11 / JEE-Main-ONLINE 2014

Sol. (2)

Q. Lithium forms body centred cubic structure. The length of the side of its unit cell is 351 pm. Atomic radius of the lithium will be :-

(1) 152 pm (2) 75 pm (3) 300 pm (4) 240 pm

Aieee-12

Sol. (1)

Q. The radius of a calcium ion is 94 pm and of the oxide ion is 146 pm. The possible crystal structure of calcium oxide will be :-

(1) Octahedral        (2) Tetrahedral          (3) Pyramidal           (4) Trigonal

Jee-Main (online)-12

Sol. (1)

Q. Ammonium chloride crystallizes in a body centred cubic lattice with edge length of unit cell of 390 pm. If the size of chloride ion is180 pm, the size of ammonium ion would be:

(1) 158 pm (2) 174 pm (3) 142 pm (4) 126 pm

Jee-Main (online)-12

Sol. (1)

Q. A solid has ‘bcc’ structure. If the distance of nearest approach between two atoms is 1.73 Å, the edge length of the cell is :-

(1) 314.20 pm (2) 216 pm (3) 200 pm (4) 1.41 pm

Jee-Main (online)-12

Sol. (3)

Q. Among the following the incorrect statement is :-

(1) Density of crystals remains unaffecfted due to Frenkel defect

(2) In BCC unit cell the void space is 32%

(3) Electrical conductivity of semiconductors and metals increases with increase in temperature

(4) Density of crystals decreases due to Schottky defect

Jee-Main (online)-12

Sol. (3)

Theory Based

Q. In a face centred cubic lattice, atoms of A form the corner points and atoms of B form the face centred points. If two atoms of A are missing from the corner points, the formula of the ionic compound is

(1) $\mathrm{AB}_{2}$

( 2) $\mathrm{AB}_{3}$

(3) $\mathrm{AB}_{4}$

(4) $\mathrm{A}_{2} \mathrm{B}_{5}$

Jee-Main (online)-13

Sol. (3)

Q. Which one of the following statements about packing in solids is incorrect ?

(1) Void space in ccp mode of packing is 26%

(2) Coordination number in hcp mode of packing is 12

(3) Void space in hcp mode of packing is 32%

(4) Coordination number in bcc mode of packing is 8

Jee-Main (online)-13

Sol. (3)

Theory based

Q. An element having an atomic radius of 0.14 nm crystallizes in an fcc unit cell. What is the length of a side of the cell ?

(1) 0.96 nm (2) 0.4 nm (3) 0.24 nm (4) 0.56 nm

Jee-Main (online)-13

Sol. (2)

Q. Expermentally it was found that a metal oxide has formula $\mathrm{M}_{0.98} \mathrm{O}$. Metal M, is present as $\mathrm{M}^{2+}$ and $\mathbf{M}^{3+}$ in its oxide. Fraction of the metal which exists as $\mathrm{M}^{3+}$ would be :-

(1) 7.01%          (2) 4.08%           (3) 6.05%           (4) 5.08

Jee-Main (offline)-13

Sol. (2)

Q. The total number of octahedral void(s) per atom present in a cubic close packed structure is :-

(1) 1          (2) 2              (3) 3              (4) 4

Jee-Main (online)-14

Sol. (1)

Theory based

Q. In a monoclinic unit cell, the relation of sides and angles are respectively

(1) $\mathrm{a} \neq \mathrm{b} \neq \mathrm{c}$ and $\alpha \neq \beta \neq \gamma \neq 90^{\circ}$

(2) $a \neq b \neq c$ and $\beta=\gamma=90^{\circ} \neq \alpha$

(3) $a=b \neq c$ and $\alpha=\beta=\gamma=90^{\circ}$

(4) $a \neq b \neq c$ and $\alpha=\beta=\gamma=90^{\circ}$

Jee-Main (online)-14

Sol. (2)

Theory based

Q. The appearance of colour in solid alkali metal halides is generally due to :

(1) Frenkel defect (2) F-centres (3) Schottky defect (4) Interstitial position

Jee-Main (online)-14

Sol. (2)

Theory based

Q. CsCl crystallises in body centred cubic lattice. if ‘a’ is its edge length then which of the following expression is correct :

(1) $\mathrm{r}_{\mathrm{Cs}^{+}}+\mathrm{r}_{\mathrm{Cl}^{-}}=\frac{\sqrt{3}}{2} \mathrm{a}$

(2) $\mathrm{r}_{\mathrm{Cs}^{+}}+\mathrm{r}_{\mathrm{Cl}^{-}}=\sqrt{3} \mathrm{a}$

(3) $\quad \mathrm{r}_{\mathrm{Cs}^{+}}+\mathrm{r}_{\mathrm{Cl}^{-}}=3 \mathrm{a}$

(4) $\mathrm{r}_{\mathrm{Cs}^{+}}+\mathrm{r}_{\mathrm{Cl}^{-}}=\frac{3 \mathrm{a}}{2}$

Jee-Main (offline)-14

Sol. (1)

Q. A metal crystallises in a face centred cubic structure. If the edge length of its unit cell is ‘a’, the closest approach between two atoms in metallic crystal will be :-

(1) 2a

(2) $2 \sqrt{2} \mathrm{a}$

(3) $\sqrt{2} \mathrm{a}$

(4) $\frac{\mathrm{a}}{\sqrt{2}}$

JEE – Main 2017

Sol. (4)

Q. Which type of ‘defect’ has the presence of cations in the interstitial sites ?

(1) Vacancy defect

(2) Frenkel defect

(3) Metal deficiency defect

(4) Schottky defect

JEE – Main 2018

Sol. (2)

In Frenkel defect, some of ion (usually cation due to their small size) missing from their correct position and occupies position in interstitial.

Nuclear Chemistry – JEE Main Previous Year Questions with Solutions

JEE Main Previous Year Papers Questions of Chemistry with Solutions are available at eSaral. Practicing JEE Mains chapter wise questions of Chemistry will help the JEE aspirants in realizing the question pattern as well as help in analyzing weak & strong areas.

Electrochemistry – JEE Main Previous Year Questions with Solutions

JEE Main Previous Year Papers Questions of Chemistry with Solutions are available at eSaral. Practicing JEE Main chapter wise questions of Chemistry will help the JEE aspirants in realizing the question pattern as well as help in analyzing weak & strong areas.

Simulator

Previous Years AIEEE/JEE Mains Questions

Q. Given :

$\mathrm{E}_{\mathrm{Fe}^{-3} / \mathrm{Fe}}^{\circ}=-0.036 \mathrm{V}, \quad \mathrm{E}_{\mathrm{Fe}^{-2} / \mathrm{Fe}}^{\circ}=-0.439 \mathrm{V}$. The value of standard electrode potential for the change.

$\mathrm{Fe}^{+3}_{(\mathrm{aq})}+\mathrm{e}^{-} \longrightarrow \mathrm{Fe}^{+2}_{(\mathrm{aq})}$ will be :-

(1) 0.770 V (2) –0.27 V (3) –0.072 V (4) 0.385 V

AIEEE 2009

Sol. (1)

$\mathrm{E}^{\circ}=\frac{3 \times-0.036+2 \times 0.439}{1}=0.77 \Rightarrow \mathrm{A}$

Q. The Gibbs energy for the decomposition of $\mathrm{Al}_{2} \mathrm{O}_{3}$ at $500^{\circ} \mathrm{C}$ is as follows :

$\frac{2}{3} \mathrm{Al}_{2} \mathrm{O}_{3} \longrightarrow \frac{4}{3} \mathrm{Al}+\mathrm{O}_{2}, \mathrm{AG}=+966 \mathrm{KJ} \mathrm{mol}^{-1}$ The potential difference needed for electrolytic reduction of $\mathrm{Al}_{2} \mathrm{O}_{3}$ at $500^{\circ} \mathrm{C}$ is at least :-

(1) 5.0 V      (2) 4.5 V       (3) 3.0 V         (4) 2.5 V

AIEEE 2010

Sol. (4)

$966 \times 10^{3}=4 \times 96500 \times \mathrm{E} \Rightarrow \mathrm{E}=2.5 \mathrm{V}$

Q. Resistance of 0.2 M solution of an electrolyte is $50 \Omega$. The specific conductance of the solution is 1.3 S $\mathrm{m}^{-1}$. If resistance of the 0.4M solution of the same electrolyte is $260 \Omega$, its molar conductivity is :-

(1) $6250 \mathrm{Sm}^{2} \mathrm{mol}^{-1}$

(2) $6.25 \times 10^{-4} \mathrm{S} \mathrm{m}^{2} \mathrm{mol}^{-1}$

(3) $625 \times 10^{-4} \mathrm{S} \mathrm{m}^{2} \mathrm{mol}^{-1}$

(4) $62.5 \mathrm{S} \mathrm{m}^{2} \mathrm{mol}^{-1}$

AIEEE 2011/JEE-MAIN 2014

Sol. (2)

Q. The reduction potential of hydrogen half-cell will be negative if :-

(1) $\mathrm{p}\left(\mathrm{H}_{2}\right)=2 \operatorname{atm}\left[\mathrm{H}^{+}\right]=1.0 \mathrm{M}$

(2) $\mathrm{p}\left(\mathrm{H}_{2}\right)=2$ atm and $\left[\mathrm{H}^{+}\right]=2.0 \mathrm{M}$

(3) $\mathrm{p}\left(\mathrm{H}_{2}\right)=1$ atm and $\left[\mathrm{H}^{+}\right]=2.0 \mathrm{M}$

(4) $\mathrm{p}\left(\mathrm{H}_{2}\right)=1$ atm and $\left[\mathrm{H}^{+}\right]=1.0 \mathrm{M}$

AIEEE 2011

Sol. (1)

Q. The standard reduction potentials for $\mathrm{Zn}^{2+} / \mathrm{Zn}, \mathrm{Ni}^{2+} / \mathrm{Ni}$ and $\mathrm{Fe}^{2+} / \mathrm{Fe}$ are $-0.76,-0.23$ and – 0.44 V respectively. The reaction $\mathrm{X}+\mathrm{Y}^{+2} \rightarrow \mathrm{X}^{2+}+\mathrm{Y}$ will be spontaneous when

(1) X = Zn, Y = Ni

(2) X = Ni, Y = Fe

(3) X = Ni, Y = Zn

(4) X = Fe, Y = Zn

Sol. (1)

For spontaneous reaction $\mathrm{E}^{\circ}>0 \mathrm{so}(\mathrm{A})$

Q. Given :

Based on the data given above, strongest oxidising agent will be :

(1) Cl–

(2) $\mathrm{Cr}^{3+}$

(3) $\mathrm{Mn}^{2+}$

(4) $\mathrm{MnO}_{4}^{-}$

JEE-Mains 2013

Sol. (4)

Higher the SRP, stronger will be oxidising agent

Hence, $\mathrm{MnO}_{4}^{-}$ is stronger oxidising agent.

Q. The equivalent conductance of NaCl at concentration C and at infinite dilution are $\lambda_{\mathrm{C}}$ and $\lambda_{\infty}$ , respectively. The correct relationship between $\lambda_{\mathrm{C}}$ and $\lambda_{\infty}$ is given as:

(1) $\lambda_{\mathrm{C}}=\lambda_{\infty}-(\mathrm{B}) \sqrt{\mathrm{C}}$

(2) $\lambda_{\mathrm{C}}=\lambda_{\infty}+(\mathrm{B}) \sqrt{\mathrm{C}}$

(3) $\lambda_{\mathrm{C}}=\lambda_{\infty}+(\mathrm{B}) \mathrm{C}$

(4) $\lambda_{\mathrm{C}}=\lambda_{\infty}-(\mathrm{B}) \mathrm{C}$

JEE-Mains 2014

Sol. (1)

Fact

Q. At 298 K, the standard reduction potentials are 1.51 V for $\mathrm{MnO}_{4}-| \mathrm{Mn}^{2+}$ , 1.36 V for $\mathrm{Cl}_{2} | \mathrm{Cl}^{-}$, 1.07 V for $\mathrm{Br}_{2} | \mathrm{Br}^{-},$ and $0.54 \mathrm{V}$ for $\mathrm{I}_{2} | \mathrm{I}^{-} .$ At $\mathrm{pH}=3$, permanganate is expected to oxidize $\left(\frac{\mathrm{RT}}{\mathrm{F}}=0.059 \mathrm{V}\right):-$

(1) $\mathrm{Cl}^{-}$ and $\mathrm{Br}^{-}$

(2) $\mathrm{Cl}^{-}, \mathrm{Br}^{-}$ and $\mathrm{I}^{-}$

(3) $\mathrm{Br}^{-}$ and $\mathrm{I}^{-}$

(4) I- only

JEE-Mains (online) 2015

Sol. (3)

Q. A variable, opposite external potential $\left(\mathrm{E}_{\mathrm{ext}}\right)$ is applied to the cell

$\mathrm{Zn}\left|\mathrm{Zn}^{2+}(1 \mathrm{M}) \| \mathrm{Cu}^{2+}(1 \mathrm{M})\right| \mathrm{Cu}$, of potential 1.1 V. When $\mathrm{E}_{\mathrm{ext}}<1.1 \mathrm{V}$ and $\mathrm{E}_{\mathrm{ext}}>1.1 \mathrm{V}$ , respectively electrons flow from :

(1) anode to cathode in both cases

(2) anode to cathode and cathode to anode

(3) cathode to anode in both cases

(4) cathode to anode and anode to cathode

JEE-Mains (online) 2015

Sol. (2)

Fact

Q. Two Faraday of electricity is passed through a solution of $\mathrm{CuSO}_{4}$. The mass of copper deposited at the cathode is :

(at. mass of Cu = 63.5 amu)

(1) 2g         (2) 127 g          (3) 0 g          (4) 63.5 g

JEE-Mains 2015

Sol. (4)

$2 \mathrm{F}=2 \mathrm{eq}=1$ mole $=63.5 \mathrm{gm}$

Q. Galvanization is applying a coating of :-

(1)Zn         (2) Pb         (3) Cr        (4) Cu

JEE-Mains 2016

Sol. (1)

Galvanization is the process of applying a protective zinc coating of steel or iron, to prevent rusting.

Q. Given

(1)Cr

(2) $\mathrm{Mn}^{2+}$

(3) $\mathrm{Cr}^{3+}$

(4) $\mathrm{Cl}^{-}$

JEE-Mains 2017

Sol. (1)

Since $\mathrm{Cr}^{+3}$ is having least reducing potential, so Cr is the best Reducing agent.

Q. How long (approximate) should water be electrolysed by passing through 100

amperes current so that the oxygen released can completely burn 27.66 g of diborane ?

(Atomic weight of B = 10.8 u)

(1)0.8 hours

(2) 3.2 hours

(3) 1.6 hours

(4) 6.4 hours

JEE-Mains 2018

Sol. (2)

Thermodynamics – JEE Main Previous Year Questions with Solutions

JEE Main Previous Year Papers Questions of Chemistry With Solutions are available at eSaral.

Simulator

Previous Years AIEEE/JEE Mains Questions

Q. In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidizer. The reaction is $\mathrm{CH}_{3} \mathrm{OH}(\ell)+\frac{3}{2} \mathrm{O}_{2}(\mathrm{g}) \longrightarrow \mathrm{CO}_{2}(\mathrm{g})+2 \mathrm{H}_{2} \mathrm{O}(\ell)$

At 298 K standard Gibb’s energies of formation for $\mathrm{CH}_{3} \mathrm{OH}(\ell), \mathrm{H}_{2} \mathrm{O}(\ell)$ and $\mathrm{CO}_{2}(\mathrm{g})$ are –166.2, –237.2 and –394.4 kJ $\mathrm{mol}^{-1}$ respectively. If standard enthalpy of combustion of methanol is –726 kJ $\mathrm{mol}^{-1}$, efficiency of the fuel cell will be

(1) 90% (2) 97% (3) 80% (4) 87%

[AIEEE-2009]

Sol. (2)

$\mathrm{CH}_{3} \mathrm{OH}(l)+\frac{3}{2} \mathrm{O}_{2}(\mathrm{g}) \rightarrow \mathrm{CO}_{2}+2 \mathrm{D}_{2} \mathrm{O}(l)$

$\Delta \mathrm{G}^{\circ}=\left(2 \Delta \mathrm{G}_{\mathrm{f}}^{\circ}\left[\mathrm{H}_{2} \mathrm{O}(l)+\Delta \mathrm{G}_{\mathrm{f}}^{\circ}\left[\mathrm{CO}_{2}(g)\right]\right)-\left(\Delta \mathrm{G}_{\mathrm{f}}^{\circ}\left[\mathrm{CH}_{3} \mathrm{OH}(l)+\frac{3}{2} \Delta \mathrm{G}_{\mathrm{F}}^{\circ}\left[\mathrm{O}_{2}(g)\right]\right)\right.\right.$

$\Delta \mathrm{G}^{\circ}=(2(-237.2)+(-394.4)-(-166.2+0)$

$\Delta \mathrm{G}^{\mathrm{o}}=-868.8+166.2$

$=-702.6 \mathrm{kJ} / \mathrm{mol}$

Cell efficiency $=\left|\frac{\Delta \mathrm{G}^{\circ}}{\Delta \mathrm{H}^{\circ}}\right| \times 100$

$=\frac{702.6}{726} \times 100=96.77 \approx 97 \%$

Q. On the basis of the following thermochemical data : $\left(\Delta \mathrm{G}_{\mathrm{f}}^{0} \mathrm{H}_{(\mathrm{a}) \mathrm{y}}^{+}=0\right)$

$\mathrm{H}_{2} \mathrm{O}(\ell) \rightarrow \mathrm{H}^{+}(\mathrm{aq})+\mathrm{OH}^{-}(\mathrm{aq}) ; \Delta \mathrm{H}=57.32 \mathrm{kJ}$

$\mathrm{H}_{2}(\mathrm{g})+\frac{1}{2} \mathrm{O}_{2}(\mathrm{g}) \rightarrow \mathrm{H}_{2} \mathrm{O}(\ell) ; \Delta \mathrm{H}=-286.20 \mathrm{kJ}$

The value of enthalpy of formation of $\mathrm{OH}^{-}$ ion at $25^{\circ} \mathrm{C}$ is :-

(1) +228.88 kJ

(2) –343.52 kJ

(3) –22.88 kJ

(4) –228.88 kJ

[AIEEE-2009]

Sol. (4)

$\mathrm{H}_{2} \mathrm{O}(l) \longrightarrow \mathrm{H}^{+}(\mathrm{aq} .)+\mathrm{OH}^{-}(\mathrm{aq} .)$

$57.32=\Delta \mathrm{H}_{\mathrm{f}}^{\mathrm{o}}\left[\mathrm{OH}^{-}(\mathrm{aq})\right]-\Delta \mathrm{H}_{\mathrm{f}}^{\mathrm{o}}\left[\mathrm{H}_{2} \mathrm{O}_{(l)}\right]$

$57.32=\Delta \mathrm{H}_{\mathrm{F}}^{\circ}\left[\mathrm{OH}_{(\mathrm{aq})}^{-}\right]+286.20$

$\Delta \mathrm{H}_{\mathrm{F}}^{\circ}\left[\mathrm{OH}^{-}_{(\mathrm{aq})}\right]=-228.88 \mathrm{kJ}$

Q. The standard enthalphy of formation of $\mathrm{NH}_{3}$ is $-46.0 \mathrm{kJ} \mathrm{mol}^{-1}$ If the enthalpy of formation of H2 from its atoms is –436 kJ $\mathrm{mol}^{-1}$ and that of $\mathrm{N}_{2}$ is $-712 \mathrm{kJ} \mathrm{mol}^{-1}$, the average bond enthalpy of N–H bond in NH3 is

(1) $-1102 \mathrm{kJ} \mathrm{mol}^{-1}$

(2) $-964 \mathrm{kJ} \mathrm{mol}^{-1}$

(3) $+352$ kJ mol $^{-1}$

(4) $+1056 \mathrm{kJ} \mathrm{mol}^{-1}$

[AIEEE-2010]

Sol. (3)

$\frac{1}{2} \mathrm{N}_{2}(\mathrm{g})+\frac{3}{2} \mathrm{H}_{2}(\mathrm{g}) \longrightarrow \mathrm{NH}_{3}(\mathrm{g})$

$-46=\frac{1}{2}(712)+\frac{3}{2}(436)-3(\mathrm{N}-\mathrm{H})$

– 46 = 356 + 654 – 3(N – H)

N – H = 352 kJ / mol

Q. Consider the reaction :

$4 \mathrm{NO}_{2}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{N}_{2} \mathrm{O}_{5}(\mathrm{g}), \Delta_{\mathrm{r}} \mathrm{H}=-111 \mathrm{kJ}$

If $\mathrm{N}_{2} \mathrm{O}_{5}(\mathrm{s})$ is formed instead of $\mathrm{N}_{2} \mathrm{O}_{5}(\mathrm{g})$ in the above reaction, the rH value will be :-

(given, of sublimation for $\mathrm{N}_{2} \mathrm{O}_{5}$ is 54 kJ \mathrm{mol}^{-1})

(1) –165 kJ

(2) +54 kJ

(3) +219 kJ

(4) –219 kJ

[AIEEE-2011]

Sol. (4)

If $\mathrm{N}_{2} \mathrm{O}_{5}(\mathrm{s})$ is formed instead of $\mathrm{N}_{2} \mathrm{O}_{5}(\mathrm{g})$ then

$\Delta_{1} \mathrm{H}=-111-2(54)$

$\Delta_{\mathrm{r}} \mathrm{H}=-111-108$

$\Delta_{1} \mathrm{H}=-219 \mathrm{kJ} / \mathrm{mol}$

Q. The enthalpy of neutralisation of \mathrm{NH}_{4} \mathrm{OH}with HCl is –51.46 kJ \mathrm{mol}^{-1} and the enthalpy of neutralisation of NaOH with HCl is –55.90 kJ $\mathrm{mol}^{-1}$ The enthalpy of ionisation of $\mathrm{NH}_{4} \mathrm{OH}$ is:

(1) $+107.36 \mathrm{kJ} \mathrm{mol}^{-1}$

(2) $-4.44 \mathrm{kJ} \mathrm{mol}^{-1}$

(3) $-107.36 \mathrm{kJ} \mathrm{mol}^{-1}$

(4) $+4.44 \mathrm{kJ} \mathrm{mo}$

[JEE-mains (online) 2012]

Sol. (4)

Q. The reaction $\mathrm{X} \rightarrow \mathrm{Y}$ is an exothermic reaction. Activation energy of the reaction for X into Y is 150 kJ $\operatorname{mol}^{-1}$. Enthalpy of reaction is 135 kJ $\mathrm{mol}^{-1}$ . The activation energy for the reverse reaction, $\mathrm{Y} \rightarrow \mathrm{X}$ will be :

(1) 15 kJ $\mathrm{mol}^{-1}$

(2) 285 kJ $\mathrm{mol}^{-1}$

(3) 270 kJ $\mathrm{mol}^{-1}$

(4) 280 kJ $\mathrm{mol}^{-1}$

Sol. (3)

$\Delta \mathrm{H}=\mathrm{E}_{\mathrm{a}(\mathrm{f})}-\mathrm{E}_{\mathrm{a}(\mathrm{b})}$

$-135=150-\mathrm{E}_{\mathrm{a}(\mathrm{b})}$

– 617 = 161 + 520 + 77 + x – 1047

x = –328 kJ/mol

Q. Given

Based on data provided, the value of electron gain enthalpy of fluorine would be :

(1) –300 kJ $\mathrm{mol}^{-1}$

(2) –328 kJ $\mathrm{mol}^{-1}$

(3) –350 kJ $\mathrm{mol}^{-1}$

(4) –228 kJ $\mathrm{mol}^{-1}$

[JEE-mains (online) 2013]

Sol. (2)

Q. Given :

The molar enthalpy of vapourisation of water will be :-

(1) 241. 8 kJ $\mathrm{mol}^{-1}$

(2) 527.7 kJ $\mathrm{mol}^{-1}$

(3) 44.1 kJ $\mathrm{mol}^{-1}$

(4) 22.0 kJ $\mathrm{mol}^{-1}$

[JEE-mains (online) 2013]

Sol. (3)

Q. The standard enthalpy of formation $\left(\Delta_{\mathrm{f}} \mathrm{H}_{298}^{\circ}\right)$ for methane, $\mathrm{CH}_{4}$ is– 74.9 kJ $\mathrm{mol}^{-1}$. In order to calculate the average energy given out in the formation of a C–H bond from this it is necessary to know which one of the following?

(1) the dissociation energy of the hydrogen molecule, $\mathrm{H}_{2}$.

(2) the dissociation energy of $\mathrm{H}_{2}$ and enthalpy of sublimation of carbon

(graphite).

(3) the first four ionisation energies of carbon and electron affinity of hydrogen.

(4) the first four ionisation energies of carbon.

[JEE-mains(online) 2014]

Sol. (2)

From formation enthalpy of methane C-H bond enthalpy can be calculated as –

$\mathrm{C}(\mathrm{s})+2 \mathrm{H}_{2}(\mathrm{g}) \longrightarrow \mathrm{CH}_{4}(\mathrm{g})$

$\Delta \mathrm{H}_{\mathrm{f}}^{\circ}\left(\mathrm{CH}_{4}(\mathrm{g})\right)=\Delta \mathrm{H}_{\mathrm{a}}^{\circ}[\mathrm{C}(\mathrm{s})]+2(\mathrm{H}-\mathrm{H})-4(\mathrm{C}-\mathrm{H})$

$(\mathrm{C}-\mathrm{H})=\frac{\Delta \mathrm{H}_{\mathrm{f}}^{\circ}\left(\mathrm{CH}_{4}(\mathrm{g})\right)-\Delta \mathrm{H}_{\mathrm{f}}^{\circ}(\mathrm{C}(\mathrm{s}))-2[\mathrm{H}-\mathrm{H}]}{4}$

So for calculating (C-H) bond we will required data of H- H bond enthalpy and sublimation enthalpy of carbon solid.

Q. For an ideal Solution of two components A and B, which of the following is true ?

(1) $\Delta \mathrm{H}_{\text {mixing }}<0$ (zero)

(2) A – A, B – B and A – B interactions are identical

(3) A – B interaction is stronger than A – A and B – B interactions

(4) $\Delta \mathrm{H}_{\text {mixing }}>0$ (zero)

[JEE-mains (online) 2014]

Sol. (1)

Q. For complete combustion of ethanol, $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}(\ell)+3 \mathrm{O}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{CO}_{2}(\mathrm{g})+3 \mathrm{H}_{2} \mathrm{O}(\ell)$the amount of heat produced as measured in bomb calorimeter, is 1364.47 kJ $\mathrm{mol}^{-1}$ at $25^{\circ} \mathrm{C}$. Assuming ideality the Enthalpy of combustion, $\Delta_{\mathrm{C}} \mathrm{H}$, for the raction will be :-

$\left(\mathrm{R}=8.314 \mathrm{kJ} \mathrm{mol}^{-1}\right)$

(1) $-1460.50 \mathrm{kj} \mathrm{mol}^{-1}$

(2) $-1350.50 \mathrm{kJ} \mathrm{mol}^{-1}$

(3) $-1366.95 \mathrm{kJ} \mathrm{mol}^{-1}$

$(4)-1361.95 \mathrm{kJ} \mathrm{mol}^{-1}$

[JEE-mains(offline)2014]

Sol. (3)

Q. The heats of combustion of carbon and carbon monoxide are – 393.5 and – 285.5 kJ $\operatorname{mol}^{-1}$, respectively. The heat of formation (in kJ) of carbon monoxide per mole is :

(1)– 110

(2) 110.5

(3) 676.5

(4) – 676.5

[JEE-Mains 2016]

Sol. (1)

Q. Given

[JEE – Main – 2017]

Sol. (3)

$\mathrm{CO}_{2}(\mathrm{g})+2 \mathrm{H}_{2} \mathrm{O}(\ell) \rightarrow \mathrm{CH}_{4}(\mathrm{g})+2 \mathrm{O}_{2}(\mathrm{g}) ; \Delta \mathrm{H}^{\circ}=890.3$

$\Delta_{\mathrm{f}} \mathrm{H}^{\circ}-393.5-285.8$

$\Delta_{\mathrm{r}} \mathrm{H}^{\circ}=\sum\left(\Delta_{\mathrm{f}} \mathrm{H}^{\circ}\right)_{\text {protucts }}-\sum\left(\Delta_{\mathrm{f}} \mathrm{H}^{\circ}\right)_{\text {Restatatis }}$

$890.3=\left[1 \times\left(\Delta_{\mathrm{f}} \mathrm{H}^{\circ}\right)_{\mathrm{CH}_{4}}+2 \times 0\right]-[1 \times(-393.5)+2(-285.8)]$

$\left(\Delta_{\mathrm{f}} \mathrm{H}^{\circ}\right)_{\mathrm{CH}_{4}}=890.3-965.1=-74.8 \mathrm{kJ} / \mathrm{mol}$

Q. The combustion of benzene (l) gives $\mathrm{CO}_{2}(\mathrm{g})$ and $\mathrm{H}_{2} \mathrm{O}(\mathrm{l})$. Given that heat of combustion

of benzene at constant volume is –3263.9 kJ $\operatorname{mol}^{-1}$ at $25^{\circ} \mathrm{C}$; heat of combustion (in kJ $\mathrm{mol}^{-1}$) of benzene at constant pressure will be – (R = 8.314 $\mathrm{JK}^{-1}$ $\mathrm{mol}^{-1}$)

(1)–452.46

(2) 3260

(3) –3267.6

(4) 4152.6

[JEE – Main – 2018]

Sol. (3)

Themochemistry – JEE Main Previous Year Questions with Solutions

JEE Main Previous Year Papers Questions of Chemistry With Solutions are available at eSaral.

Simulator

Previous Years AIEEE/JEE Mains Questions

Q. In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidizer. The reaction is $\mathrm{CH}_{3} \mathrm{OH}(\ell)+\frac{3}{2} \mathrm{O}_{2}(\mathrm{g}) \longrightarrow \mathrm{CO}_{2}(\mathrm{g})+2 \mathrm{H}_{2} \mathrm{O}(\ell)$

At 298 K standard Gibb’s energies of formation for $\mathrm{CH}_{3} \mathrm{OH}(\ell), \mathrm{H}_{2} \mathrm{O}(\ell)$ and $\mathrm{CO}_{2}(\mathrm{g})$ are –166.2, –237.2 and –394.4 kJ $\mathrm{mol}^{-1}$ respectively. If standard enthalpy of combustion of methanol is –726 kJ $\mathrm{mol}^{-1}$, efficiency of the fuel cell will be

(1) 90% (2) 97% (3) 80% (4) 87%

[AIEEE-2009]

Sol. (2)

$\mathrm{CH}_{3} \mathrm{OH}(l)+\frac{3}{2} \mathrm{O}_{2}(\mathrm{g}) \rightarrow \mathrm{CO}_{2}+2 \mathrm{D}_{2} \mathrm{O}(l)$

$\Delta \mathrm{G}^{\circ}=\left(2 \Delta \mathrm{G}_{\mathrm{f}}^{\circ}\left[\mathrm{H}_{2} \mathrm{O}(l)+\Delta \mathrm{G}_{\mathrm{f}}^{\circ}\left[\mathrm{CO}_{2}(g)\right]\right)-\left(\Delta \mathrm{G}_{\mathrm{f}}^{\circ}\left[\mathrm{CH}_{3} \mathrm{OH}(l)+\frac{3}{2} \Delta \mathrm{G}_{\mathrm{F}}^{\circ}\left[\mathrm{O}_{2}(g)\right]\right)\right.\right.$

$\Delta \mathrm{G}^{\circ}=(2(-237.2)+(-394.4)-(-166.2+0)$

$\Delta \mathrm{G}^{\mathrm{o}}=-868.8+166.2$

$=-702.6 \mathrm{kJ} / \mathrm{mol}$

Cell efficiency $=\left|\frac{\Delta \mathrm{G}^{\circ}}{\Delta \mathrm{H}^{\circ}}\right| \times 100$

$=\frac{702.6}{726} \times 100=96.77 \approx 97 \%$

Q. On the basis of the following thermochemical data : $\left(\Delta \mathrm{G}_{\mathrm{f}}^{0} \mathrm{H}_{(\mathrm{a}) \mathrm{y}}^{+}=0\right)$

$\mathrm{H}_{2} \mathrm{O}(\ell) \rightarrow \mathrm{H}^{+}(\mathrm{aq})+\mathrm{OH}^{-}(\mathrm{aq}) ; \Delta \mathrm{H}=57.32 \mathrm{kJ}$

$\mathrm{H}_{2}(\mathrm{g})+\frac{1}{2} \mathrm{O}_{2}(\mathrm{g}) \rightarrow \mathrm{H}_{2} \mathrm{O}(\ell) ; \Delta \mathrm{H}=-286.20 \mathrm{kJ}$

The value of enthalpy of formation of $\mathrm{OH}^{-}$ ion at $25^{\circ} \mathrm{C}$ is :-

(1) +228.88 kJ

(2) –343.52 kJ

(3) –22.88 kJ

(4) –228.88 kJ

[AIEEE-2009]

Sol. (4)

$\mathrm{H}_{2} \mathrm{O}(l) \longrightarrow \mathrm{H}^{+}(\mathrm{aq} .)+\mathrm{OH}^{-}(\mathrm{aq} .)$

$57.32=\Delta \mathrm{H}_{\mathrm{f}}^{\mathrm{o}}\left[\mathrm{OH}^{-}(\mathrm{aq})\right]-\Delta \mathrm{H}_{\mathrm{f}}^{\mathrm{o}}\left[\mathrm{H}_{2} \mathrm{O}_{(l)}\right]$

$57.32=\Delta \mathrm{H}_{\mathrm{F}}^{\circ}\left[\mathrm{OH}_{(\mathrm{aq})}^{-}\right]+286.20$

$\Delta \mathrm{H}_{\mathrm{F}}^{\circ}\left[\mathrm{OH}^{-}_{(\mathrm{aq})}\right]=-228.88 \mathrm{kJ}$

Q. The standard enthalphy of formation of $\mathrm{NH}_{3}$ is $-46.0 \mathrm{kJ} \mathrm{mol}^{-1}$ If the enthalpy of formation of H2 from its atoms is –436 kJ $\mathrm{mol}^{-1}$ and that of $\mathrm{N}_{2}$ is $-712 \mathrm{kJ} \mathrm{mol}^{-1}$, the average bond enthalpy of N–H bond in NH3 is

(1) $-1102 \mathrm{kJ} \mathrm{mol}^{-1}$

(2) $-964 \mathrm{kJ} \mathrm{mol}^{-1}$

(3) $+352$ kJ mol $^{-1}$

(4) $+1056 \mathrm{kJ} \mathrm{mol}^{-1}$

[AIEEE-2010]

Sol. (3)

$\frac{1}{2} \mathrm{N}_{2}(\mathrm{g})+\frac{3}{2} \mathrm{H}_{2}(\mathrm{g}) \longrightarrow \mathrm{NH}_{3}(\mathrm{g})$

$-46=\frac{1}{2}(712)+\frac{3}{2}(436)-3(\mathrm{N}-\mathrm{H})$

– 46 = 356 + 654 – 3(N – H)

N – H = 352 kJ / mol

Q. Consider the reaction :

$4 \mathrm{NO}_{2}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{N}_{2} \mathrm{O}_{5}(\mathrm{g}), \Delta_{\mathrm{r}} \mathrm{H}=-111 \mathrm{kJ}$

If $\mathrm{N}_{2} \mathrm{O}_{5}(\mathrm{s})$ is formed instead of $\mathrm{N}_{2} \mathrm{O}_{5}(\mathrm{g})$ in the above reaction, the rH value will be :-

(given, of sublimation for $\mathrm{N}_{2} \mathrm{O}_{5}$ is 54 kJ \mathrm{mol}^{-1})

(1) –165 kJ

(2) +54 kJ

(3) +219 kJ

(4) –219 kJ

[AIEEE-2011]

Sol. (4)

If $\mathrm{N}_{2} \mathrm{O}_{5}(\mathrm{s})$ is formed instead of $\mathrm{N}_{2} \mathrm{O}_{5}(\mathrm{g})$ then

$\Delta_{1} \mathrm{H}=-111-2(54)$

$\Delta_{\mathrm{r}} \mathrm{H}=-111-108$

$\Delta_{1} \mathrm{H}=-219 \mathrm{kJ} / \mathrm{mol}$

Q. The enthalpy of neutralisation of \mathrm{NH}_{4} \mathrm{OH}with HCl is –51.46 kJ \mathrm{mol}^{-1} and the enthalpy of neutralisation of NaOH with HCl is –55.90 kJ $\mathrm{mol}^{-1}$ The enthalpy of ionisation of $\mathrm{NH}_{4} \mathrm{OH}$ is:

(1) $+107.36 \mathrm{kJ} \mathrm{mol}^{-1}$

(2) $-4.44 \mathrm{kJ} \mathrm{mol}^{-1}$

(3) $-107.36 \mathrm{kJ} \mathrm{mol}^{-1}$

(4) $+4.44 \mathrm{kJ} \mathrm{mo}$

[JEE-mains (online) 2012]

Sol. (4)

Q. The reaction $\mathrm{X} \rightarrow \mathrm{Y}$ is an exothermic reaction. Activation energy of the reaction for X into Y is 150 kJ $\operatorname{mol}^{-1}$. Enthalpy of reaction is 135 kJ $\mathrm{mol}^{-1}$ . The activation energy for the reverse reaction, $\mathrm{Y} \rightarrow \mathrm{X}$ will be :

(1) 15 kJ $\mathrm{mol}^{-1}$

(2) 285 kJ $\mathrm{mol}^{-1}$

(3) 270 kJ $\mathrm{mol}^{-1}$

(4) 280 kJ $\mathrm{mol}^{-1}$

Sol. (3)

$\Delta \mathrm{H}=\mathrm{E}_{\mathrm{a}(\mathrm{f})}-\mathrm{E}_{\mathrm{a}(\mathrm{b})}$

$-135=150-\mathrm{E}_{\mathrm{a}(\mathrm{b})}$

– 617 = 161 + 520 + 77 + x – 1047

x = –328 kJ/mol

Q. Given

Based on data provided, the value of electron gain enthalpy of fluorine would be :

(1) –300 kJ $\mathrm{mol}^{-1}$

(2) –328 kJ $\mathrm{mol}^{-1}$

(3) –350 kJ $\mathrm{mol}^{-1}$

(4) –228 kJ $\mathrm{mol}^{-1}$

[JEE-mains (online) 2013]

Sol. (2)

Q. Given :

The molar enthalpy of vapourisation of water will be :-

(1) 241. 8 kJ $\mathrm{mol}^{-1}$

(2) 527.7 kJ $\mathrm{mol}^{-1}$

(3) 44.1 kJ $\mathrm{mol}^{-1}$

(4) 22.0 kJ $\mathrm{mol}^{-1}$

[JEE-mains (online) 2013]

Sol. (3)

Q. The standard enthalpy of formation $\left(\Delta_{\mathrm{f}} \mathrm{H}_{298}^{\circ}\right)$ for methane, $\mathrm{CH}_{4}$ is– 74.9 kJ $\mathrm{mol}^{-1}$. In order to calculate the average energy given out in the formation of a C–H bond from this it is necessary to know which one of the following?

(1) the dissociation energy of the hydrogen molecule, $\mathrm{H}_{2}$.

(2) the dissociation energy of $\mathrm{H}_{2}$ and enthalpy of sublimation of carbon

(graphite).

(3) the first four ionisation energies of carbon and electron affinity of hydrogen.

(4) the first four ionisation energies of carbon.

[JEE-mains(online) 2014]

Sol. (2)

From formation enthalpy of methane C-H bond enthalpy can be calculated as –

$\mathrm{C}(\mathrm{s})+2 \mathrm{H}_{2}(\mathrm{g}) \longrightarrow \mathrm{CH}_{4}(\mathrm{g})$

$\Delta \mathrm{H}_{\mathrm{f}}^{\circ}\left(\mathrm{CH}_{4}(\mathrm{g})\right)=\Delta \mathrm{H}_{\mathrm{a}}^{\circ}[\mathrm{C}(\mathrm{s})]+2(\mathrm{H}-\mathrm{H})-4(\mathrm{C}-\mathrm{H})$

$(\mathrm{C}-\mathrm{H})=\frac{\Delta \mathrm{H}_{\mathrm{f}}^{\circ}\left(\mathrm{CH}_{4}(\mathrm{g})\right)-\Delta \mathrm{H}_{\mathrm{f}}^{\circ}(\mathrm{C}(\mathrm{s}))-2[\mathrm{H}-\mathrm{H}]}{4}$

So for calculating (C-H) bond we will required data of H- H bond enthalpy and sublimation enthalpy of carbon solid.

Q. For an ideal Solution of two components A and B, which of the following is true ?

(1) $\Delta \mathrm{H}_{\text {mixing }}<0$ (zero)

(2) A – A, B – B and A – B interactions are identical

(3) A – B interaction is stronger than A – A and B – B interactions

(4) $\Delta \mathrm{H}_{\text {mixing }}>0$ (zero)

[JEE-mains (online) 2014]

Sol. (1)

Q. For complete combustion of ethanol, $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}(\ell)+3 \mathrm{O}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{CO}_{2}(\mathrm{g})+3 \mathrm{H}_{2} \mathrm{O}(\ell)$the amount of heat produced as measured in bomb calorimeter, is 1364.47 kJ $\mathrm{mol}^{-1}$ at $25^{\circ} \mathrm{C}$. Assuming ideality the Enthalpy of combustion, $\Delta_{\mathrm{C}} \mathrm{H}$, for the raction will be :-

$\left(\mathrm{R}=8.314 \mathrm{kJ} \mathrm{mol}^{-1}\right)$

(1) $-1460.50 \mathrm{kj} \mathrm{mol}^{-1}$

(2) $-1350.50 \mathrm{kJ} \mathrm{mol}^{-1}$

(3) $-1366.95 \mathrm{kJ} \mathrm{mol}^{-1}$

$(4)-1361.95 \mathrm{kJ} \mathrm{mol}^{-1}$

[JEE-mains(offline)2014]

Sol. (3)

Q. The heats of combustion of carbon and carbon monoxide are – 393.5 and – 285.5 kJ $\operatorname{mol}^{-1}$, respectively. The heat of formation (in kJ) of carbon monoxide per mole is :

(1)– 110

(2) 110.5

(3) 676.5

(4) – 676.5

[JEE-Mains 2016]

Sol. (1)

Q. Given

[JEE – Main – 2017]

Sol. (3)

$\mathrm{CO}_{2}(\mathrm{g})+2 \mathrm{H}_{2} \mathrm{O}(\ell) \rightarrow \mathrm{CH}_{4}(\mathrm{g})+2 \mathrm{O}_{2}(\mathrm{g}) ; \Delta \mathrm{H}^{\circ}=890.3$

$\Delta_{\mathrm{f}} \mathrm{H}^{\circ}-393.5-285.8$

$\Delta_{\mathrm{r}} \mathrm{H}^{\circ}=\sum\left(\Delta_{\mathrm{f}} \mathrm{H}^{\circ}\right)_{\text {protucts }}-\sum\left(\Delta_{\mathrm{f}} \mathrm{H}^{\circ}\right)_{\text {Restatatis }}$

$890.3=\left[1 \times\left(\Delta_{\mathrm{f}} \mathrm{H}^{\circ}\right)_{\mathrm{CH}_{4}}+2 \times 0\right]-[1 \times(-393.5)+2(-285.8)]$

$\left(\Delta_{\mathrm{f}} \mathrm{H}^{\circ}\right)_{\mathrm{CH}_{4}}=890.3-965.1=-74.8 \mathrm{kJ} / \mathrm{mol}$

Q. The combustion of benzene (l) gives $\mathrm{CO}_{2}(\mathrm{g})$ and $\mathrm{H}_{2} \mathrm{O}(\mathrm{l})$. Given that heat of combustion

of benzene at constant volume is –3263.9 kJ $\operatorname{mol}^{-1}$ at $25^{\circ} \mathrm{C}$; heat of combustion (in kJ $\mathrm{mol}^{-1}$) of benzene at constant pressure will be – (R = 8.314 $\mathrm{JK}^{-1}$ $\mathrm{mol}^{-1}$)

(1)–452.46

(2) 3260

(3) –3267.6

(4) 4152.6

[JEE – Main – 2018]

Sol. (3)

States of Matter – JEE Main Previous Year Questions with Solutions

JEE Main Previous Year Papers Questions of Chemistry With Solutions are available at eSaral.

Simulator

Previous Years AIEEE/JEE Mains Questions

Q. The molecular velocity of any gas is :-

(1) inversely proportional to the square root of temperature

(2) inversely proportional to absolute temperature

(3) directly proportional to square of temperature

(4) directly proportional to square root of temperature

[AIEEE-2011]

Sol. (4)

Q. , v and u represent most probable velocity, average velocity and root mean

square

velocity respectively of a gas at a particular temperature. The correct order among the

following is –

(1)  > u > v

(2) v > u > 

(3) u > v > 

(4) u >  > v

[JEE(Main)-2012]

Sol. (3)

Q. An open vessel at 300 K is heated till $\frac{2}{5}$th of the air in it is expelled.

Assuming that the

volume of the vessel remains constant, the temperature to which the vessel is heated is :-

(1) 750 K

(2) 400 K

(3) 500 K

(4) 1500K

[JEE(Main-online)-2012]

Sol. (3)

Q. For 1 mol of an ideal gas at constant temperature T, the plot of (log P)

against(logV) is a (P : Pressure, V : Volume) :-

(1) Straight line parallel to x-axis

(2) Curve starting at origin]

(3) Straight line with a negative slope

(4) Straight line passing through origin

[JEE(Main-online)-2012]

Sol. (3)

PV = nRT

log (PV) = log (nRT)

log P + log V = log (nRT)

log P = –log V + log (nRT)

y = – mx + C

slope $=\tan \theta=-1$

Q. The relationship among most probable velocity, average velocity and root mean

square

velocity is respectively :-

(1) $\sqrt{2}: \sqrt{8 / \pi}: \sqrt{3}$

(2) $\sqrt{2}: \sqrt{3}: \sqrt{8 / \pi}$

(3) $\sqrt{3}: \sqrt{8 / \pi}: \sqrt{2}$

(4) $\sqrt{8 / \pi}: \sqrt{3}: \sqrt{2}$

[JEE(Main-online)-2012]

Sol. (1)

Q. Which one of the following is the wrong assumption of kinetic theory of gases ?

(1) All the molecules move in straight line between collision and with same velocity.

(2) Molecules are separated by great distances compared to their sizes.

(3) Pressure is the result of elastic collision of molecules with the container’s wall.

(4) Momentum and energy always remain conserved.

[JEE(Main-online)-2013]

Sol. (1)

Q. By how many folds the temperature of a gas would increase when the root mean

square

velocity of the gas molecules in a container of fixed volume is increased from $5 \times 10^{4} \mathrm{cm} /$

s to $10 \times 10^{4} \mathrm{cm} / \mathrm{s} ?$

(1) Four

(2) three

(3) Two

(4) Six

[JEE(Main-online)-2013]

Sol. (1)

$\mathrm{u}_{\mathrm{rms}} \propto \sqrt{\mathrm{T}}$

$\left(\frac{5 \times 10^{4}}{10 \times 10^{4}}\right)=\frac{\mathrm{T}_{1}}{\mathrm{T}_{2}}$

$\frac{1}{4}=\frac{T_{1}}{T_{2}}$

$\mathrm{T}_{2}=4 \mathrm{T}_{1}$

Q. For gaseous state, if most probable speed is denoted by C, average speed by $\overline{\mathrm{c}}$ and

mean

square speed by C, then for a large number of molecules the ratios of these speeds are :-

(1) $\mathrm{C}: \overline{\mathrm{C}}: \mathrm{C}=1.225: 1.128: 1$

(2) $\mathrm{C}: \overline{\mathrm{C}}: \mathrm{C}=1.128: 1.225: 1$

(3) $\mathrm{C}: \overline{\mathrm{C}}: \mathrm{C}=1: 1.128: 1.225$

(4) $\mathrm{C}: \overline{\mathrm{C}}: \mathrm{C}=1: 1.225: 1.128$

[JEE(Main-offline)-2013]

Sol. (3)

$\mathrm{u}_{\mathrm{avg}}=\sqrt{\frac{8 \mathrm{RT}}{\pi \mathrm{M}}}$

$\mathrm{u}_{\mathrm{rms}}=\sqrt{\frac{3 \mathrm{RT}}{\mathrm{M}}}$

$\mathrm{u}_{\mathrm{mp}}=\sqrt{\frac{2 \mathrm{RT}}{\mathrm{M}}}$

Q. A gaseous compound of nitrogen and hydrogen contains 12.5%(by mass) of

hydrogen.

The density of the compound relative to hydrogen is 16. The molecular formula of the

compound is :

(1) $\mathrm{NH}_{2}$

(2) $\mathrm{NH}_{3}$

(3) $\mathrm{N}_{3} \mathrm{H}$

(4) $\mathrm{N}_{2} \mathrm{H}_{4}$

[JEE(Main-online)-2014]

Sol. (4)

Q. The initial volume of a gas cylinder is 750.0 mL. If the pressure of gas inside the

cylinder changes from 840.0 mm Hg to 360.0 mm Hg, the final volume the gas will be

(1)1.750 L

(2) 7.50 L

(3) 3.60 L

(4) 4.032 L

[JEE(Main-online)-2014]

Sol. (1)

$\mathrm{P}_{1} \mathrm{V}_{1}=\mathrm{P}_{2} \mathrm{V}_{2}$

$840 \times 750=360 \times \mathrm{V}_{2}$

$\mathrm{V}_{2}=\frac{840 \times 750}{360}$

Q. The temperature at which oxygen molecules have the same root mean square

speed as

helium atoms have at 300 K is :

(Atomic masses : He = 4 u, O = 16 u)

(1) 1200 K

(2) 600 K

(3) 300 K

(4) 2400 K

[JEE(Main-online)-2014]

Sol. (4)

Q. Two closed bulbs of equal volume(V) containing an ideal gas initially at pressure

pi and temperature $\mathrm{T}_{1}$ are connected through a narrow tube of negligible

volume as shown in the figure below. The temperature of one of the bulbs is then raised to

$\mathrm{T}_{2}$. The final pressure $\mathrm{P}_{\mathrm{f}}$ is :-

[JEE(Main)-2016]

Sol. (4)

Initial moles and final moles are equal

$\left(\mathrm{n}_{\mathrm{T}}\right)_{\mathrm{i}}=\left(\mathrm{n}_{\mathrm{T}}\right)_{\mathrm{f}}$

$\frac{\mathrm{P}_{\mathrm{i}} \mathrm{V}}{\mathrm{RT}_{1}}+\frac{\mathrm{P}_{\mathrm{i}} \mathrm{V}}{\mathrm{RT}_{1}}=\frac{\mathrm{P}_{\mathrm{f}} \mathrm{V}}{\mathrm{RT}_{1}}+\frac{\mathrm{P}_{\mathrm{f}} \mathrm{V}}{\mathrm{RT}_{2}}$

$2 \frac{\mathrm{P}_{\mathrm{i}}}{\mathrm{T}_{\mathrm{i}}}=\frac{\mathrm{P}_{\mathrm{i}}}{\mathrm{T}_{\mathrm{i}}}+\frac{\mathrm{P}_{\mathrm{i}}}{\mathrm{T}_{2}}$

$\mathrm{P}_{\mathrm{f}}=\frac{2 \mathrm{P}_{\mathrm{i}} \mathrm{T}_{2}}{\mathrm{T}_{1}+\mathrm{T}_{2}}$

Q. ‘a’ and ‘b’ are Vander Waal’s constants for gases. Chlorine is more easily liquefied than ethane

because :-

[Aieee-2012]

Sol. (2)

Higher the ‘a’ value, more easily the gas is liquified, lower the ‘b’ value, more easily the gas is liquified

Q. The compressibility factor for a real gas at high pressure is :-

(1) $1-\frac{\text { Pb }}{\mathrm{RT}}$

(2) $1+\frac{\mathrm{RT}}{\mathrm{Pb}}$

(3) 1

(4) $1+\frac{\mathrm{Pb}}{\mathrm{RT}}$

[Aieee-2012]

Sol. (4)

At high pressure, repulsion dominate.

$\left(\mathrm{P}+\frac{\mathrm{a}}{\mathrm{Vm}^{2}}\right)(\mathrm{Vm}-\mathrm{b})=\mathrm{RT}$

P(Vm – b) = RT

$\mathrm{So}, \mathrm{Z}=1+\frac{\mathrm{Pb}}{\mathrm{RT}}$

Q. If Z is the compressibility factor, van der Waals’ equation at low pressure can be written as :

$(1) Z=1-\frac{\mathrm{Pb}}{\mathrm{RT}}$

$(2) Z=1+\frac{\mathrm{Pb}}{\mathrm{RT}}$

(3) $\mathrm{Z}=1+\frac{\mathrm{RT}}{\mathrm{Pb}}$

(4) $\mathrm{Z}=1-\frac{\mathrm{a}}{\mathrm{V}_{\mathrm{m}} \mathrm{RT}}$

[JEE-MAINS-2014]

Sol. (4)

At low pressure, attractions dominate.

$\left(\mathrm{P}+\frac{\mathrm{a}}{\mathrm{Vm}^{2}}\right)(\mathrm{Vm}-\mathrm{b})=\mathrm{RT}$

$\left(\mathrm{P}+\frac{\mathrm{a}}{\mathrm{Vm}^{2}}\right)(\mathrm{Vm})=\mathrm{RT}$

$\mathrm{So}, \mathrm{Z}=1-\frac{\mathrm{a}}{\mathrm{VmRT}}$

Q. When does a gas deviate the most from it’s ideal behaviour ?

(1) At high pressure and low temperature

(2) At high pressure and high temperature

(3) At low pressure and low temperature

(4) At low pressure and high temperature

[JEEMAINS(online)-2015]

Sol. (1)

Gas behaves most ideally at high T and low P while deviates most from ideal behaviour at high P and low T.

Redox Reaction – JEE Main Previous Year Questions with Solutions

JEE Main Previous Year Papers Questions of Chemistry With Solutions are available at eSaral.

Simulator

Previous Years AIEEE/JEE Mains Questions

Q. Consider the following reaction:

$\mathrm{xMnO}_{4}^{-}+\mathrm{yC}_{2} \mathrm{O}_{4}^{2-}+\mathrm{ZH}^{+} \rightarrow$

$\mathrm{xMn}^{2+}+2 \mathrm{yCO}_{2}+\frac{\mathrm{Z}}{2} \mathrm{H}_{2} \mathrm{O}$

The values of x, y and z in the reaction are respectively :-

(1) 5,2 and 16

(2) 2,5 and 8

(3) 2, 5 and 16

(4) 5,2 and 8

[JEE(Main)-2013]

Sol. (3)

Fact

Q. Given :

$\mathrm{X} \mathrm{Na}_{2} \mathrm{HAsO}_{3}+\mathrm{Y} \mathrm{NaBrO}_{3}+\mathrm{ZHCl} \rightarrow \mathrm{NaBr}$ $+\mathrm{H}_{3} \mathrm{AsO}_{4}+\mathrm{NaCl}$

The values of X, Y and Z in the above redox reaction are respectively :

(1) 2, 1, 3

(2) 3, 1, 6

(3) 2, 1, 2

(4) 3, 1, 4

[JEE(Main-online)-2013]

Sol. (2)

Fact

Q. In which of the following reaction $\mathrm{H}_{2} \mathrm{O}_{2}$ acts as a reducing agent ?

(1) $\mathrm{H}_{2} \mathrm{O}_{2}+2 \mathrm{H}^{+}+2 \mathrm{e}^{-} \rightarrow 2 \mathrm{H}_{2} \mathrm{O}$

(2) $\mathrm{H}_{2} \mathrm{O}_{2}-2 \mathrm{e}^{-} \rightarrow \mathrm{O}_{2}+2 \mathrm{H}^{+}$

(3) $\mathrm{H}_{2} \mathrm{O}_{2}+2 \mathrm{e}^{-} \rightarrow 2 \mathrm{OH}^{-}$

(4) $\mathrm{H}_{2} \mathrm{O}_{2}+2 \mathrm{OH}^{-}-2 \mathrm{e}^{-} \rightarrow \mathrm{O}_{2}+2 \mathrm{H}_{2} \mathrm{O}$

(1) (1), (3)

(2) (2), (4)

(3) (1), (2)

(4) (3), (4)

[JEE(Main-online)-2014]

Sol. (2)

Fact

Q. Consider the reaction

$\mathrm{H}_{2} \mathrm{SO}_{3(\mathrm{aq})}+\mathrm{Sn}_{(\mathrm{aq})}^{4+}+\mathrm{H}_{2} \mathrm{O}_{(\mathrm{l})} \rightarrow \mathrm{Sn}_{(\mathrm{aq})}^{2+}+\mathrm{HSO}_{4(\mathrm{aq})}^{-}+3 \mathrm{H}_{(\mathrm{aq})}^{+}$

Which of the following statements is correct?

(1) $\mathrm{H}_{2} \mathrm{SO}_{3}$ is the reducing agent because it undergoes oxidation

(2) $\mathrm{H}_{2} \mathrm{SO}_{3}$ is the reducing agent because it undergoes reduction

(3) $\mathrm{Sn}^{4+}$ is the reducing agent because it undergoes oxidation

(4) $\mathrm{Sn}^{4+}$ is the oxidizing agent because it undergoes oxidation

[JEE(Main-online)-2014]

Sol. (1)

Fact

Q. How many electrons are involved in the following redox reaction ?

$\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}+\mathrm{Fe}^{2+}+\mathrm{C}_{2} \mathrm{O}_{4}^{2-} \rightarrow \mathrm{Cr}^{3+}+\mathrm{Fe}^{3+}+\mathrm{CO}_{2}$ (Unbalanced)

(1) 3 (2) 4 (3) 5 (4) 6

[JEE(Main-online)-2014]

Sol. (4)

Fact

Q. Which of the following reactions is an example of a redox reaction ?

(1) $\mathrm{XeF}_{4}+\mathrm{O}_{2} \mathrm{F}_{2} \rightarrow \mathrm{XeF}_{6}+\mathrm{O}_{2}$

(2) $\mathrm{XeF}_{2}+\mathrm{PF}_{5} \rightarrow[\mathrm{XeF}]^{+} \mathrm{PF}_{6}^{-}$

(3) $\mathrm{XeF}_{6}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{XeOF}_{4}+2 \mathrm{HF}$

(4) $\mathrm{XeF}_{6}+2 \mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{XeO}_{2} \mathrm{F}_{2}+4 \mathrm{HF}$

[JEE-Main 2017]

Sol. (1)

In the reaction

$\stackrel{+4}{\mathrm{X}} \mathrm{e} \mathrm{F}_{4}+\mathrm{O}_{2} \mathrm{F}_{2} \rightarrow \stackrel{+6}{\mathrm{X}} \mathrm{eF}_{6}+\mathrm{O}_{2}^{0}$

Xenon undergoes oxidation while oxygen undergoes reduction.

Q. An alkali is titrated against an acid with methyl orange as indicator, which of the following is a correct combination ?

[JEE-Main 2018]

Sol. (2)

Methyl orange shows Red(pinkish) color in Acidic medium & yellow color in basic medium

since original solution is basic so

initial color  yellow

& Titrated with acid so

Final color  pinkish (red)

Mole Concept – JEE Main Previous Year Questions with Solutions

JEE Main Previous Year Papers Questions of Chemistry With Solutions are available at eSaral.

Simulator

Previous Years AIEEE/JEE Mains Questions

Q. A 5.2 molal aqueous solution of methyl alcohol, $\mathrm{CH}_{3} \mathrm{OH}$, is supplied. What is the mole fraction of methyl alcohol in the solution ?

(1) 0.086           (2) 0.050             (3) 0.100             (4) 0.190

[AIEEE-2011]

Sol. (1)

$5.2 \mathrm{m} \mathrm{CH}_{3} \mathrm{OH}$ ie $5.2 \mathrm{mol} \mathrm{CH}_{3} \mathrm{OH}$ present in $1 \mathrm{kg}$ water

$\mathrm{X}_{\mathrm{M}}=\frac{5.2}{5.2+\frac{1000}{18}}=\frac{5.2}{5.2+55.5}=\frac{5.2}{60.7}=.086$

Q. The concentrated sulphuric acid that is peddled commercially is 95% $\mathrm{H}_{2} \mathrm{SO}_{4}$ by weight. If the density of this commerical acid is 1.834 g $\mathrm{cm}^{-3}$, the molarity of this solution is :-

(1) 17.8 M         (2) 15.7 M           (3) 10.5 M           (4) 12.0 M

[aieee-2012]

Sol. (1)

$95 \% \frac{\mathrm{w}}{\mathrm{w}} \mathrm{H}_{2} \mathrm{SO}_{4}$ i.e. $100 \mathrm{gm}$ contain $95 \mathrm{gm} \mathrm{H}_{2} \mathrm{SO}_{4}$

Molarity $=\frac{95 / 98}{100 / 1.834} \times 1000$

$=\frac{95 \times 1.834}{98 \times 100} \times 1000=1.78$

Q. The density of a solution prepared by dissolving 120 g of urea (mol. mass = 60 u) in 1000 g of water is 1.15 g/mL. The molarity of this solution is

(1) 2.05 M           (2) 0.50 M            (3) 1.78 M             (4) 1.02 M

[AIEEE-2012]

Sol. (1)

Mass of Solution = 120 + 1000 = 1120 gm

Vol of solution $=\frac{\text { mass }}{\text { density }}$

$=\frac{1120}{1.15} \mathrm{ml}$

Molarity $=\frac{120 / 60}{1120 / 1.15}=\frac{2 \times 1.15}{1120} \times 1000=2.05 \mathrm{M}$

Q. A transition metal M forms a volatile chloride which has a vapour density of 94.8. If it contains 74.75% of chlorine the formula of the metal chloride will be

(1) $\mathrm{MCl}_{2}$

(2) $\mathrm{MCl}_{4}$

(3) $\mathrm{MCl}_{5}$

(4) $\mathrm{MCl}_{3}$

[AIEEE 2012 (Online)]

Sol. (2)

Mol. wt = 189.6

mass of $\mathrm{C} \ell=\frac{74.75}{100} \times 189.6=141.7 \mathrm{gm}$

formula: $\mathrm{MCl}_{4}$

Q. The ratio of number of oxygen atoms (O) in 16.0g ozone $\left(\mathrm{O}_{3}\right)$, 28.0 g carbon monoxide (CO) and 16.0g oxygen $\left(\mathrm{O}_{2}\right)$ is :

(Atomic mass : $\mathrm{C}=12, \mathrm{O}=16$ and Avogadro’s constant $\mathrm{N}_{\mathrm{A}}=6.0 \times 10^{23} \mathrm{mol}^{-1}$ )

(1) 3 : 1 : 1         (2) 1 : 1 : 2            (3) 3 : 1 : 2            (4) 1 : 1 : 1

[AIEEE 2012 (Online)]

Sol. (4)

$\frac{16}{48} \times 3 \times \mathrm{N}_{\mathrm{A}}: \frac{28}{28} \times 1 \times \mathrm{N}_{\mathrm{A}}: \frac{16}{32} \times 2 \times \mathrm{N}_{\mathrm{A}}$

1 : 1 : 1

Q. When $\mathrm{CO}_{2}$ (g) is passed over red hot coke it partially gets reduced to CO(g). Upon passing 0.5 litre of $\mathrm{CO}_{2}$ (g) over red hot coke, the total volume of the gases increased to 700 mL. The composition of the gaseous mixture at STP is :-

(1) $\mathrm{CO}_{2}=200 \mathrm{mL} ; \mathrm{CO}=500 \mathrm{mL}$

(2) $\mathrm{CO}_{2}=350 \mathrm{mL} ; \mathrm{CO}=350 \mathrm{mL}$

(3) $\mathrm{CO}_{2}=0.0 \mathrm{mL} ; \mathrm{CO}=700 \mathrm{mL}$

(4) $\mathrm{CO}_{2}=300 \mathrm{mL} ; \mathrm{CO}=400 \mathrm{mL}$

[AIEEE 2012 (Online)]

Sol. (4)

Q. An open vessel at 300 K is heated till $\frac{2}{5}$ th of the air in it is expelled. Assuming that the volume of the vessel remains constant, the temperature to which the vessel is heated is :-

(1) 750 K        (2) 400 K            (3) 500 K          (4) 1500K

[AIEEE 2012 (Online)]

Sol. (3)

Q. The density of 3M solution of sodium chloride is 1.252 g $\mathrm{mL}^{-1}$. The molality of the solution will be (molar mass, NaCl = 58.5 g $\mathrm{mol}^{-1}$)

(1) 2.18 m          (2) 3.00 m            (3) 2.60 m           (4) 2.79 m

[JEE(Main-online)-2013]

Sol. (4)

$\mathrm{m}=\frac{\mathrm{M} \times 1000}{1000 \mathrm{d}-\mathrm{MMw}}=\frac{3 \times 1000}{1000 \times 1.252-3 \times 58.5}$

$=\frac{3000}{1252-175.5}=\frac{3000}{1076.5}=2.79$

Q. 10 mL of 2(M) NaOH solution is added to 200 mL of 0.5 (M) of NaOH solution. What is the final concentration ?

(1) 0.57 M          (2) 5.7 M              (3) 11.4 M            (4) 1.14 M

[JEE(Main-online)-2013]

Sol. (1)

$\mathrm{M}_{\mathrm{f}}=\frac{2 \times 10+0.5 \times 200}{210}$

$=\frac{20+100}{210}=\frac{120}{210}=.57$

Q. Number of atoms in the following samples of substances is the largest in :

(1) 127.0g of iodine

(2) 48.0g of magnesium

(3) 71.0g of chlorine

(4) 4.0g of hydrogen

[JEE(Main) 2013 (Online)]

Sol. (4)

Q. A gaseous hydrocarbon gives upon combustion 0.72 g of water and 3.08 g of CO2. The empirical formula of the hydrocarbon is

(1) $\mathrm{C}_{2} \mathrm{H}_{4}$

(2) $\mathrm{C}_{3} \mathrm{H}_{4}$

( 3) $\mathrm{C}_{6} \mathrm{H}_{5}$

(4) $\mathrm{C}_{7} \mathrm{H}_{8}$

[JEE(Main)-2013]

Sol. (4)

$\mathrm{C}_{\mathrm{x}} \mathrm{H}_{\mathrm{y}}+\left(\mathrm{x}+\frac{\mathrm{y}}{4}\right) \mathrm{O}_{2} \rightarrow \mathrm{x} \mathrm{CO}_{2}+\frac{\mathrm{y}}{2} \mathrm{H}_{2} \mathrm{O}$

a’ moles $\quad$ xa’ $\quad\left(\frac{\mathrm{y}}{2} \times \mathrm{a}\right)$

$\frac{\mathrm{x}}{\mathrm{y} / 2}=\frac{3.08 / 44}{0.72 / 18}=\mathrm{C}_{7} \mathrm{H}_{8}$

Q. For the estimation of nitrogen, 1.4 g of an organic compound was digested by Kjeldahl method and the evolved ammonia was absorbed in 60 mL of $\frac{\mathrm{M}}{10}$ sulphuric acid. The unreacted acid required 20 mL of $\frac{\mathrm{M}}{10}$ sodium hydroxide for complete neutralizaton. The percentage of nitrogen in the compound is :

(1) 3% (2) 5% (3) 6% (4) 10%

[JEE(Main-online)-2014]

Sol. (4)

Q. The amount of $\mathrm{BaSO}_{4}$ formed upon mixing 100 mL of 20.8% $\mathrm{BaCl}_{2}$ solution with 50 mL of 9.8% $\mathrm{H}_{2} \mathrm{SO}_{4}$ solution will be :

(Ba = l37, Cl = 35.5, S=32, H = l and O = 16)

(1) 33.2 g           (2) 11.65 g            (3) 23.3 g             (4) 30.6 g

[JEE(Main-online)-2014]

Sol. (2)

Q. The ratio of masses of oxygen and nitrogen in a particular gaseous mixture is 1 : 4. The ratio of number of their molecule is :

(1) 1 : 8         (2) 3 : 16           (3) 1 : 4          (4) 7 : 32

[JEE(Main)-2014]

Sol. (4)

Given $\frac{\mathrm{W}_{\mathrm{O}_{2}}}{\mathrm{W}_{\mathrm{N}_{2}}}=\frac{1}{4} \Rightarrow \frac{\mathrm{n}_{\mathrm{O}_{2}}}{\mathrm{n}_{\mathrm{N}_{2}}}=\frac{\mathrm{W}_{\mathrm{O}_{2}} \times \mathrm{M}_{\mathrm{N}_{2}}}{\mathrm{W}_{\mathrm{N}_{2}} \times \mathrm{M}_{\mathrm{O}_{2}}}=\frac{1}{4} \times \frac{28}{32}=\frac{7}{32}$

Q. The molecular formula of a commercial resin used for exchanging ions in water softening is $\mathrm{C}_{8} \mathrm{H}_{7} \mathrm{SO}_{3} \mathrm{Na}$ (Mol. w.t 206). What would be the maximum uptake of $\mathrm{Ca}^{2+}$ ions by the resin when expressed in mole per gram resin ?

(1) $\frac{2}{309}$         (2) $\frac{1}{412}$           (3) $\frac{1}{103}$             (4) $\frac{1}{206}$

[JEE(Main)-2015]

Sol. (2)

For softening of hard water by ion exchange resin method, reaction involved is

Q. 3g of activated charcoal was added to 50 mL of acetic acid solution (0.06N) in a flask. After an hour it was filtered and the strength of the filtrate was found to be 0.042 N. The amount of acetic acid adsorbed (per gram of charcoal) is :

(1) 42 mg         (2) 54 mg          (3) 18 mg          (4) 36 mg

[JEE(Main)-2015]

Sol. (3)

$\because$ Number of moles of $\mathrm{CH}_{3} \mathrm{COOH}$ adsorbed $=(0.06-0.042) \times \frac{50}{1000}$

$\therefore$ Amount of $\mathrm{CH}_{3} \mathrm{COOH}$ adsorbed per gram of charcoal $=\frac{0.018 \times 50}{1000} \times \frac{60}{3}=0.018 \mathrm{gm}$

= 18 mg

Q. In Carius method of estimation of halogens, 250 mg of an organic compound gave 141 mg of AgBr. The percentage of bromine in the compound is : (at. mass Ag = 108; Br = 80)

(1) 48        (2) 60        (3) 24           (4) 36

[JEE(Main)-2015]

Sol. (3)

Q. At 300 K and 1 atm, 15 mL of a gaseous hydrocarbon requires 375 mL air containing 20% $\mathrm{O}_{2}$ by volume for complete combustion. After combustion the gases occupy 330 mL. Assuming that the water formed is in liquid form and the volumes were measured at the same temperature and pressure, the formula of the hydrocarbon is :-

(1) $\mathrm{C}_{4} \mathrm{H}_{10}$

(2) $\mathrm{C}_{3} \mathrm{H}_{6}$

(3) $\mathrm{C}_{3} \mathrm{H}_{8}$

(4) $\mathrm{C}_{4} \mathrm{H}_{8}$

[JEE(Main)-2016]

Sol. (3)

If further information (i.e., 330 ml) is neglected, option (3) only satisfy the above equation.

Q. The concentration of fluoride, lead, nitrate and iron in a water sample from an underground lake was found to be 1000 ppb, 40 ppb, 100 ppm and 0.2 ppm, respectively. This water is unsuitable for drinking due to high concentration of :-

(1) Iron             (2) Fluoride              (3) Lead             (4) Nitrate

[JEE Main-2016]

Sol. (4)

Q. The most abundant elements by mass in the body of a healthy human adult are :

Oxygen (61.4%) ; Carbon (22.9%), Hydrogen (10.0%) ; and Nitrogen (2.6%). The weight which a 75 kg person would gain if all 1H atoms are replaced by $^{2} \mathrm{H}$ atoms is

(1) 15 kg             (2) 37.5 kg              (3) 7.5 kg              (4) 10 kg

[JEE(Main)-2017]

Sol. (3)

Mass in the body of a healthy human adult has :-

Oxygen = 61.4%, Carbon = 22.9%,

Hydrogen = 10.0% and Nitrogen = 2.6%

Total weight of person = 75 kg

Mass due to $1 \mathrm{H}$ is $=75 \times \frac{10}{100}=7.5 \mathrm{kg}$

$^{1} \mathrm{H}$ atoms are replaced by $^{2} \mathrm{H}$ atoms.

So mass gain by person =7.5 kg

Q. 1 gram of a carbonate $\left(\mathrm{M}_{2} \mathrm{CO}_{3}\right)$ on treatment with excess HCl produces 0.01186 mole of $\mathrm{CO}_{2}$. the molar mass of $\mathrm{M}_{2} \mathrm{CO}_{3}$ in g $\mathrm{mol}^{-1}$ is :-

(1) 1186            (2) 84.3             (3) 118.6             (4) 11.86

[JEE(Main)-2017]

Sol. (2)

Given chemical eq $^{\mathrm{n}}$

$\mathrm{M}_{2} \mathrm{CO}_{3}+2 \mathrm{HCl} \longrightarrow 2 \mathrm{MCl}+\mathrm{H}_{2} \mathrm{O}+\mathrm{CO}_{2}$

1gm 0.01186mol

$\Rightarrow$ from the balanced chemical $\mathrm{eq}^{\mathrm{n}}$

$\frac{1}{\mathrm{M}}=0.01186$

.

Q. A water sample has ppm level concentration of following anions

$\mathrm{F}^{-}=10 ; \mathrm{SO}_{4}^{2-}=100 ; \mathrm{NO}_{3}^{-}=50$

the anion/anions that make / makes the water sample unsuitable for drinking is / are :

(1) only $\mathrm{NO}_{3}^{-}$

(2) both $\mathrm{SO}_{4}^{2-}$ and $\mathrm{NO}_{3}^{-}$

(3) only $\mathrm{F}^{-}$

(4) only $\mathrm{SO}_{4}^{2-}$

[JEE – Main 2017]

Sol. (3)

$\mathrm{NO}_{3}^{-}$ : The maximum limit of nitrate in drinking water is 50 ppm. Excess nitrate in drinking

water can cause disease. Such as methemoglobinemia.

$\mathrm{SO}_{4}^{2-}:$ above 500 ppm of $\mathrm{SO}_{4}^{2-}$ ion in drinking water causes laxative effect otherwise at moderate levels it is harmless

$\mathrm{F}^{-}$ : Above 2ppm concentration of $\mathrm{F}^{-}$ in drinking water cause brown mottling of teeth.

The concentration given in question of $\mathrm{SO}_{4}^{2-} \& \mathrm{NO}_{3}^{-}$ in water is suitable for drinking but the concentration of $\mathrm{F}^{-}$ (i.e 10 ppm) make water unsuitable for drinking purp

Q. The ratio of mass percent of C and H of an organic compound $\left(\mathrm{C}_{\mathrm{x}} \mathrm{H}_{\mathrm{Y}} \mathrm{O}_{\mathrm{Z}}\right)$ is 6 : 1. If one molecule of the above compound $\left(\mathrm{C}_{\mathrm{x}} \mathrm{H}_{\mathrm{Y}} \mathrm{O}_{\mathrm{Z}}\right)$ contains half as much oxygen as required to burn one molecule of compound $\mathrm{C}_{\mathrm{X}} \mathrm{H}_{\mathrm{Y}}$ completely to $\mathrm{CO}_{2}$ and $\mathrm{H}_{2} \mathrm{O}$. The empirical formula of compound $\mathrm{C}_{\mathrm{X}} \mathrm{H}_{\mathrm{Y}} \mathrm{O}_{\mathrm{Z}}$ is :

(1) $\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O}$

(2) $\mathrm{C}_{3} \mathrm{H}_{4} \mathrm{O}_{2}$

(3) $\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O}_{3}$

(4) $\mathrm{C}_{3} \mathrm{H}_{6} \mathrm{O}_{3}$

[JEE(Main)-2018]

Sol. (3)

Ionic Equilibrium – JEE Main Previous Year Questions with Solutions

JEE Main Previous Year Papers Questions of Chemistry With Solutions are available at eSaral.

Simulator

Previous Years AIEEE/JEE Mains Questions

Q. Solid Ba$\left(\mathrm{NO}_{3}\right)_{2}$ is gradully dissolved in a 1.0 × $10^{-4} \mathrm{M} \mathrm{Na}_{2} \mathrm{CO}_{3}$ solution.At what concentration of Ba2+ will a precipitate begin to form? $\left(\mathrm{K}_{\mathrm{SP}} \text { for } \mathrm{Ba} \mathrm{CO}_{3}=5.1 \times 10^{-9}\right)$

(A) $8.1 \times 10^{-8} \mathrm{M}$

(B) $8.1 \times 10^{-7} \mathrm{M}$

(C) $4.1 \times 10^{-5} \mathrm{M}$

(D) $5.1 \times 10^{-5} \mathrm{M}$

[AIEEE-2009,JEE-MAIN(Online)–2013]

Sol. (D)

$5.1 \times 10^{-9}=\left[\mathrm{Ba}^{+2}\right]\left[10^{-4}\right]$

$\left[\mathrm{Ba}^{+2}\right]=5.1 \times 10^{-5} \mathrm{M}$

Q. At 25° C, the solubility producct of $\mathrm{Mg}(\mathrm{OH})_{2}$ is $1.0 \times 10^{-11}$. At which pH, will $\mathrm{Mg}^{2+}$ ions start precipitating in the form of $\mathrm{Mg}(\mathrm{OH})_{2}$ from a solution of 0.001 M $\mathrm{Mg}^{2+}$ ions?

(A) 8                     (B) 9                        (C) 10                             (D) 11

[AIEEE–2010]

Sol. (C)

$10^{-11}=\left[\mathrm{Mg}^{+2}\right]\left[\mathrm{OH}^{-}\right]^{2}$

$10^{-11}=\left(10^{-3}\right)\left[\mathrm{OH}^{-}\right]^{2}$

$\left[\mathrm{OH}^{-}\right]=10^{-4} \quad \mathrm{pOH}=4 \quad \mathrm{pH}=11$

Q. In aqueous solution the ionization constants for carbonic acid are $\mathrm{K}_{1}=4.2 \times 10^{-7}$ and $\mathrm{K}_{2}=4.8$ $\times 10^{-11}$ Select the correct statement for a saturated 0.034 M solution of the carbonic acid :-

(A) The concentration of $\mathrm{H}^{+}$ is double that of $\mathrm{CO}_{3}^{2-}$

(B) The concentration of $\mathrm{CO}_{3}^{2-}$ is $0.034 \mathrm{M}$

(C) The concentration of $\mathrm{CO}_{3}^{2-}$ is greater than that of $\mathrm{HCO}_{3}^{-}$

(D) The concentrations of $\mathrm{H}^{+}$ and $\mathrm{HCO}_{3}^{-}$ are approximately equal

[AIEEE–2010]

Sol. (D)

Q. Solubility product of silver bromide is $5.0 \times 10^{-13}$. The quantity of potassium bromide (molar mass taken as 120 g $\left.\mathrm{mol}^{-1}\right)$ to be added to 1 litre of 0.05 M solution of silver nitrate to start the precipitation of AgBr is :-

(A) $5.0 \times 10^{-8} \mathrm{g}$

(B) $1.2 \times 10^{-10} \mathrm{g}$

(C) $1.2 \times 10^{-9} \mathrm{g}$

(D) $6.2 \times 10^{-5} \mathrm{g}$

[AIEEE–2010]

Sol. (C)

$\left[\mathrm{Ag}^{+}\right]\left[\mathrm{Br}^{-}\right]=\mathrm{Ksp}$

$[0.05]\left[\frac{\mathrm{W}}{120}\right]=5 \times 10^{-13}$

$\mathrm{w}=\frac{120 \times 5 \times 10^{-13}}{5 \times 10^{-2}}=120 \times 10^{-11}=12 \times 10^{-10}$

$=1.2 \times 10^{-9} \mathrm{g}$

Q. An acid HA ionises as

The pH of 1.0 M solution is 5. Its dissociation constant would be :-

(A) $1 \times 10^{-10}$

(B) 5

(C) $5 \times 10^{-8}$

(D) $1 \times 10^{-5}$

[AIEEE–2011]

Sol. (A)

$\left[\mathrm{H}^{+}\right]=10^{-5}=\mathrm{C}_{\mathrm{o}} \alpha$

$\alpha=10^{-5}$

Q. The $\mathrm{K}_{\mathrm{sp}}$ for $\mathrm{Cr}(\mathrm{OH})_{3}$ is $1.6 \times 10^{-30}$ The molar solubility of this compound in water is :-

(A) $\sqrt[2]{1.6 \times 10^{-30}}$

(B) $\sqrt[4]{1.6 \times 10^{-30}}$

(C) $\sqrt[4]{1.6 \times 10^{-30} / 27}$

(D) $1.6 \times 10^{-30 / 27}$

[AIEEE–2011]

Sol. (C)

$\mathrm{Ksp}=1.6 \times 10^{-30}=27 \mathrm{S}^{4}$

$S^{4}=\left[\frac{1.6 \times 10^{-30}}{27}\right]$

$S=\left[\frac{1.6 \times 10^{-30}}{27}\right]^{1 / 4}$

Q. The pH of a 0.1 molar solution of the acid HQ is 3. The value of the ionization constant, Ka of this acid is :-

(A) $1 \times 10^{-7}$

(B) $3 \times 10^{-7}$

(C) $1 \times 10^{-3}$

(D) $1 \times 10^{-5}$

[AIEEE–2012]

Sol. (D)

[\mathrm{HQ}]=0.10 \mathrm{M}

\alpha=10^{-2}

Q. If $\mathrm{K}_{\mathrm{sp}}$ of $\mathrm{CaF}_{2}$ at $25^{\circ} \mathrm{C}$ is $1.7 \times 10^{-10}$ , the combination amongst the following which gives a precipitate of $\mathrm{CaF}_{2}$ is :-

(A) $1 \times 10^{-2} \mathrm{M} \mathrm{Ca}^{2+}$ and $1 \times 10^{-5} \mathrm{M} \mathrm{F}^{-}$

(B) $1 \times 10^{-4} \mathrm{M} \mathrm{Ca}^{2+}$ and $1 \times 10^{-4} \mathrm{M} \mathrm{F}^{-}$

(C) $1 \times 10^{-3} \mathrm{M} \mathrm{Ca}^{2+}$ and $1 \times 10^{-5} \mathrm{M} \mathrm{F}^{-}$

(D) $1 \times 10^{-2} \mathrm{M} \mathrm{Ca}^{2+}$ and $1 \times 10^{-3} \mathrm{M} \mathrm{F}^{-}$

[JEE-MAIN(online)–2012]

Sol. (D)

Q. How many litres of water must be added to 1 litre of an aqueous solution of HCl with a pH of 1 to create an aqueous solution with pH of 2 ?

(A) 0.1 L             (B) 0.9 L              (C) 2.0 L            (D) 9.0 L

[AIEEE–2013]

Sol. (D)

\left(10^{-1}\right)(1)=\left(10^{-2}\right)(1+\mathrm{v})

10=\mathrm{v}+1

v = 9L

Q. What would be the pH of a solution obtained by mixing 5 g of acetic acid and 7.5 g of sodium acetate and making the volume equal to 500 mL?

$\left(\mathrm{Ka}=1.75 \times 10^{-5}, \mathrm{pKa}=4.76\right)$

(A) 4.76 < pH < 5.0

(B) pH < 4.70

(C) pH of solution will be equal to pH of acetic acid

(D) pH = 4.70

[JEE-MAIN(Online)–2013]

Sol. (A)

Q. Which one of the following arrangements represents the correct order of solubilities of sparingly soluble salts $\mathrm{Hg}_{2} \mathrm{Cl}_{2}, \mathrm{Cr}_{2}\left(\mathrm{SO}_{4}\right)_{3}, \mathrm{BaSO}_{4}$ and $\mathrm{CrCl}_{3}$ respectively ?

(A) $\left(\frac{\mathrm{K}_{\mathrm{sp}}}{4}\right)^{\frac{1}{3}},\left(\frac{\mathrm{K}_{\mathrm{sp}}}{108}\right)^{\frac{1}{3}},\left(\mathrm{K}_{\mathrm{sp}}\right)^{\frac{1}{2}},\left(\frac{\mathrm{K}_{\mathrm{sp}}}{27}\right)^{\frac{1}{4}}$

(B) $\left(\mathrm{K}_{\mathrm{ap}}\right)^{\frac{1}{2}},\left(\frac{\mathrm{K}_{\mathrm{sp}}}{4}\right)^{\frac{1}{3}},\left(\frac{\mathrm{K}_{\mathrm{gp}}}{27}\right)^{\frac{1}{4}},\left(\frac{\mathrm{K}_{\mathrm{sp}}}{108}\right)^{\frac{1}{3}}$

(C) $\left(\mathrm{K}_{\mathrm{sp}}\right)^{\frac{1}{2}},\left(\frac{\mathrm{K}_{\mathrm{sp}}}{108}\right)^{\frac{1}{3}},\left(\frac{\mathrm{K}_{\mathrm{sp}}}{27}\right)^{\frac{1}{4}},\left(\frac{\mathrm{K}_{\mathrm{sp}}}{4}\right)^{\frac{1}{3}}$

$(\mathrm{D})\left(\frac{\mathrm{K}_{\mathrm{sp}}}{108}\right)^{\frac{1}{3}},\left(\frac{\mathrm{K}_{\mathrm{sp}}}{27}\right)^{\frac{1}{4}},\left(\mathrm{K}_{\mathrm{sp}}\right)^{\frac{1}{2}},\left(\frac{\mathrm{K}_{\mathrm{sp}}}{4}\right)^{\frac{1}{3}}$

[JEE-MAIN(Online)–2013]

Sol. (A)

Q. NaOH is a strong base. What will be pH of 5.0 × $10^{-2} \mathrm{M}$ NaOH solution ? (log2 = 0.3)

(A) 13.70             (B) 13.00             (C) 14.00             (D) 12.70

[JEE-MAIN(Online)–2013]

Sol. (D)

Q. Zirconium phosphate $\left[\mathrm{Zr}_{3}\left(\mathrm{PO}_{4}\right)_{4}\right]$ dissociates into three zirconium cations of charge +4 and four phosphate anions of charge –3. If molar solubility of zirconium phosphate is denoted by S and its solubility product by $\mathrm{K}_{\mathrm{sp}}$ then which of the following relationship between S and $\mathrm{K}_{\mathrm{sp}}$is correct ?

(A) $\mathrm{S}=\left\{\mathrm{K}_{\mathrm{sp}} / 144\right\}^{1 / 7}$

(B) $\mathrm{S}=\left\{\mathrm{K}_{\mathrm{sp}} /(6912)^{1 / 7}\right\}$

(C) $\mathrm{S}=\left(\mathrm{K}_{\mathrm{sp}} / 6912\right)^{1 / 7}$

(D) $\mathrm{S}=\left\{\mathrm{K}_{\mathrm{sp}} / 6912\right\}^{7}$

[JEE-MAIN(Online)–2014]

Sol. (C)

Q. In some solutions, the concentration of $\mathrm{H}_{3} \mathrm{O}^{+}$ remains constant even when small amounts of strong acid or strong base are added to them. These solutions are known as :-

(A) Colloidal solutions (B) True solutions

(C) Ideal solutions (D) Buffer solutions

[JEE-MAIN(Online)–2014]

Sol. (D)

Q. An aqueous solution contains 0.10 M $\mathrm{H}_{2} \mathrm{S}$ and 0.20 M HCl. If the equilibrium constants for the formation of HS– from H2S is 1.0 × $10^{-7}$ and that of $\mathrm{S}^{2-}$ from $\mathrm{HS}^{-}$ ions is 1.2×$10^{-13}$ then the concentration of $\mathrm{S}^{2-}$ ions in aqueous solution is :

(A) $3 \times 10^{-20}$

(B) $6 \times 10^{-21}$

(C) $5 \times 10^{-19}$

(D) $5 \times 10^{-8}$

[JEE-MAIN–2018]

Sol. (A)

Chemical Equilibrium – JEE Mains Previous Year Questions

JEE Main Previous Year Papers Questions of Chemistry With Solutions are available at eSaral.

Simulator

Previous Years AIEEE/JEE Mains Questions

Q. A vessel at 1000 K contains $\mathrm{CO}_{2}$ with a pressure of 0.5 atm. Some of the $\mathrm{CO}_{2}$ is converted into CO on the addition of graphite. If the total pressure at equilibrium is 0.8 atm, the value of K is :-

(1) 0.3 atm (2) 0.18 atm (3) 1.8 atm (4) 3 atm

[AIEEE-2011]

Sol. (3)

Q. The equilibrium constant $\left(\mathrm{K}_{\mathrm{C}}\right)$ for the reaction $\mathrm{N}_{2}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{g}) \longrightarrow 2 \mathrm{NO}(\mathrm{g})$ at temperature T is $4 \times 10^{-4}$ The value of $\mathrm{K}_{\mathrm{c}}$ for the reaction. $\mathrm{NO}(\mathrm{g}) \longrightarrow 1 / 2 \mathrm{N}_{2}(\mathrm{g})+1 / 2 \mathrm{O}_{2}(\mathrm{g})$ at the same temperature is :-

(1) 50.0

(2) 0.02

(3) $2.5 \times 10^{2}$

(4) $4 \times 10^{-4}$

[AIEEE-2012]

Sol. (1)

$\mathrm{K}_{\mathrm{c}}=\frac{1}{\sqrt{\mathrm{K}_{\mathrm{c}}}}$

Q. 8 mol of $\mathrm{AB}_{3}(\mathrm{g})$ are introduced into a 1.0 $\mathrm{d} \mathrm{m}^{3}$ vessel. If it dissociates as $2 \mathrm{AB}_{3}(\mathrm{g}) \square \quad \mathrm{A}_{2}(\mathrm{g})+3 \mathrm{B}_{2}(\mathrm{g})$

At equilibrium, 2mol of $\mathrm{A}_{2}$ are found to be present. The equilibrium constant of this reaction is :-

(1) 36 (2) 3 (3) 27 (4) 2

[JEE-MAINS(online)-2012]

Sol. (3)

Q. The value of Kp for the equilibrium reaction $\mathrm{N}_{2} \mathrm{O}_{4}(\mathrm{g}) \square 2 \mathrm{NO}_{2}(\mathrm{g})$ is 2 The percentage dissociation of $\mathrm{N}_{2} \mathrm{O}_{4}(\mathrm{g})$ at a pressure of 0.5 atm is

(1) 71 (2) 50 (3) 88 (4) 25

[JEE-MAINS(online)-2012]

Sol. (1)

$\mathrm{K}_{\mathrm{p}}=\frac{(2 \alpha)^{2}}{(1-\alpha)} \times \frac{0.5}{(1+\alpha)}$

Q. $\mathrm{K}_{1}, \mathrm{K}_{2}$ and $\mathrm{K}_{3}$ are the equilibrium constants of the following reactions (I), (II) and (III), respectively

(I) $\mathrm{N}_{2}+2 \mathrm{O}_{2} \square 2 \mathrm{NO}_{2}$

(II) $2 \mathrm{NO}_{2} \square \mathrm{N}_{2}+2 \mathrm{O}_{2}$

(III) $\mathrm{NO}_{2} \square \frac{1}{2} \mathrm{N}_{2}+\mathrm{O}_{2}$

The correct relation from the following is :

(1) $\mathrm{K}_{1}=\sqrt{\mathrm{K}_{2}}=\mathrm{K}_{3}$

(2) $\mathrm{K}_{1}=\frac{1}{\mathrm{K}_{2}}=\frac{1}{\mathrm{K}_{3}}$

$(3) \mathrm{K}_{1}=\frac{1}{\mathrm{K}_{2}}=\mathrm{K}_{3}$

(4)$\mathrm{K}_{1}=\frac{1}{\mathrm{K}_{2}}=\frac{1}{\left(\mathrm{K}_{3}\right)^{2}}$

[JEE-MAINS(online)-2012]

Sol. (4)

Fact

Q. One mole of $\mathrm{O}_{2}(\mathrm{g})$ and two moles of SO2(g) were heated in a closed vessel of one litre capacity at 1098 K. At equilibrium 1.6 moles of $\mathrm{SO}_{3}$ (g) were found. The equilibrium constant $\mathbf{K}_{C}$ of the reaction would be :-

(1) 60 (2) 80 (3) 30 (4) 40

[JEE-MAINS(online)-2012]

Sol. (2)

Q. $\mathrm{N}_{2}(\mathrm{g})+3 \mathrm{H}_{2}(\mathrm{g}) \square 2 \mathrm{NH}_{3}(\mathrm{g}), \mathrm{K}_{1}$

$\mathrm{N}_{2}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{g}) \square 2 \mathrm{NO}(\mathrm{g}), \mathrm{K}_{2} \quad(\mathrm{B})$

$\mathrm{H}_{2}(\mathrm{g})+\frac{1}{2} \mathrm{O}_{2}(\mathrm{g}) \square \mathrm{H}_{2} \mathrm{O}(\mathrm{g}), \mathrm{K}_{3} \quad(\mathrm{C})$

The equation for the equilibrium constant of the reaction

$2 \mathrm{NH}_{3}(\mathrm{g})+\frac{5}{2} \mathrm{O}_{2}(\mathrm{g}) \square 2 \mathrm{NO}(\mathrm{g})+3 \mathrm{H}_{2} \mathrm{O}(\mathrm{g}),\left(\mathrm{K}_{4}\right)$

in terms of $\mathrm{K}_{1}, \mathrm{K}_{2}$ and $\mathrm{K}_{3}$ is :

(1) $\frac{\mathrm{K}_{1} \mathrm{K}_{3}^{2}}{\mathrm{K}_{2}}$

(2) $\frac{\mathrm{K}_{2} \mathrm{K}_{3}^{3}}{\mathrm{K}_{1}}$

(3) $\frac{\mathrm{K}_{1} \mathrm{K}_{2}}{\mathrm{K}_{3}}$

(4) $\mathrm{K}_{1} \mathrm{K}_{2} \mathrm{K}_{3}$

[JEE-MAINS(online)-2013]

Sol. (2)

Fact

Q. In reaction $\mathrm{A}+2 \mathrm{B} \square 2 \mathrm{C}+\mathrm{D}$, initial concentration of B was 1.5 times of |A|, but at equilibrium the concentrations of A and B became equal. The equilibrium constant for the reaction is

(1)4 (2) 6 (3) 12 (4) 8

[JEE-MAINS(online)-2013]

Sol. (1)

$\mathrm{K}_{\mathrm{c}}=4$

Q. For the decomposition of the compound, represented as

If the reaction is started with 1 mol of the compound, the total pressure at equilibrium would be

(1) $38.8 \times 10^{-2}$ atm

(2) $1.94 \times 10^{-2}$ atm

(3) $5.82 \times 10^{-2}$ atm

(4) $7.66 \times 10^{-2}$ atm

[JEE-MAINS(online)-2014]

Sol. (3)

Q. For the reaction $\mathrm{SO}_{2(\mathrm{g})}+\frac{1}{2} \mathrm{O}_{2(\mathrm{g})} \square \mathrm{SO}_{3(\mathrm{g})},$ if $\mathrm{K}_{\mathrm{p}}=\mathrm{K}_{\mathrm{C}}(\mathrm{RT})^{\mathrm{x}}$ where the symbols have usual meaning then the value of x is : (assuming ideality)

( 1)$\frac{1}{2}$

( 2) 1

(3) –1

$(4)-\frac{1}{2}$

[JEE-MAINS 2014]

Sol. (4)

$\mathrm{K}_{\mathrm{p}}=\mathrm{K}_{\mathrm{C}}(\mathrm{RT})^{-\frac{1}{2}}$

Q. The equilibrium constants at 298 K for a reaction $\mathrm{A}+\mathrm{B} \rightleftharpoons \mathrm{C}+\mathrm{D}$ is 100 If the initial concentration of all the four species were 1 M each, then equilibrium concentration of D

(in mol $\mathrm{L}^{-1}$) will be :

(1) 1.182 (2) 0.182 (3) 0.818 (4) 1.818

[JEE-Mains 2016]

Sol. (4)

Atomic Structure – JEE Main Previous Year Questions with Solutions

JEE Main Previous Year Papers Questions of Chemistry With Solutions are available at eSaral.

Simulator

Previous Years AIEEE/JEE Mains Questions

Q. In an atom, an electron is moving with a speed of 600 m/s with an accuracy of 0.005%. Certainity with which the position of the electron can be located is ($\mathrm{Ch}=6.6 \times 10^{-34} \mathrm{kg} \mathrm{m}^{2} \mathrm{s}^{-1}$, mass of electron,

$\mathrm{e}_{\mathrm{m}}=9.1 \times 10^{-31} \mathrm{kg}$):-

(1) $1.92 \times 10^{-3} \mathrm{m}$

(2) $3.84 \times 10^{-3} \mathrm{m}$

(3) $1.52 \times 10^{-4} \mathrm{m}$

(4) $5.10 \times 10^{-3} \mathrm{m}$

[AIEEE-2009]

Sol. (1)

Q. Calculate the wavelength (in nanometer) associated with a proton moving at $1.0 \times 10^{3} \mathrm{ms}^{-1}$ (Mass of proton = $1.67 \times 10^{-27} \mathrm{kg}$ and $\mathrm{h}=6.63 \times 10^{-34} \mathrm{Js}$) :-

(1) 2.5 nm (2) 14.0 nm (3) 0.032 nm (4) 0.40 nm

[AIEEE-2009]

Sol. (4)

$\mathrm{m}_{\mathrm{p}}=1.67 \times 10^{-27}$

$\mathrm{h}=6.63 \times 10^{-34}$

$\mathrm{v}=10^{3}$

$\lambda=\frac{\mathrm{h}}{\mathrm{mv}}=\frac{6.63 \times 10^{-34}}{1.67 \times 10^{-27} \times 10^{3}}$

$=3.97 \times 10^{-7+3}$

$=3.97 \times 10^{-10}$

$=\frac{3.9 \times 10^{-10}}{10^{-9}} \mathrm{nm} \quad=0.40 \mathrm{nm}$

Q. The energy required to break one mole of Cl–Cl bonds in Cl2 is 242 kJ $\mathrm{mol}^{-1}$. The longest wavelength of light capable of breaking a single Cl–Cl bond is

$\left(\mathrm{C}=3 \times 10^{8} \mathrm{ms}^{-1} \text { and } \mathrm{N}_{\mathrm{A}}=6.02 \times 10^{23} \mathrm{mol}^{-1}\right)$

(1) 494 nm

(2) 594 nm

(3) 640 nm

(4) 700 nm

[AIEEE-2010]

Sol. (1)

$\mathrm{B.E.}=242 \mathrm{kJ} / \mathrm{mol}$

$\mathrm{E}=\frac{\mathrm{hcN}_{\mathrm{A}}}{\lambda}$

$10^{3} \times 242 \times \lambda=3 \times 10^{8} \times 6.626 \times 10^{-34} \times 6.02 \times 10^{23}$

$\lambda=\frac{3 \times 6.626 \times 6.02 \times 10^{-26+23}}{242}$

$=0.494 \times 10^{-3} \times 10^{-3}$

= 494 nm

Q. Ionisation energy of $\mathrm{He}^{+}$ is $19.6 \times 10^{-18} \mathrm{J}$ atom $^{-1}$. The energy of the first stationary state (n = 1) of $\mathrm{L} \mathbf{i}^{2+}$ is:-

(1) $8.82 \times 10^{-17} \mathrm{J}$ atom $^{-1}$

(2) $4.41 \times 10^{-16} \mathrm{J}$ atom $^{-1}$

(3) $-4.41 \times 10^{-17} \mathrm{J}$ atom $^{-1}$

(4) $-2.2 \times 10^{-15} \mathrm{J}$ atom $^{-1}$

[AIEEE-2010]

Sol. (3)

I.E. $=19.6 \times 10^{-18}$

I.E $\propto \mathrm{z}^{2}$

$\frac{(\mathrm{I.E.})_{\mathrm{Li}^{+2}}}{(\mathrm{I.E.})_{\mathrm{He}}}=\frac{\mathrm{Z}_{\mathrm{Li}}^{2}}{\mathrm{Z}_{\mathrm{He}}^{2}} \quad \mathrm{E}_{1}=\frac{9}{4} \times 19.6 \times 10^{-18}$

$=-4.41 \times 10^{-17}$

Q. The frequency of light emitted for the transition n = 4 to n = 2 of He+ is equal to the transition in H atom corresponding to which of the following

(1) n = 3 to n = 1 (2) n = 2 to n = 1 (3) n = 3 to n = 2 (4) n = 4 to n = 3

[AIEEE-2011]

Sol. (2)

Q. The electrons identified by quantum numbers n and  :-

(a) n = 4 ,  = 1

(b) n = 4,  = 0

(c) n = 3,  = 2

(d) n = 3,  = 1

Can be placed in order of increasing energy as

(1) (a) < (c) < (b) < (d) (2) (c) < (d) < (b) < (a)

(3) (d) < (b) < (c) < (a) (4) (b) < (d) < (a) < (c)

(3) (d) < (b) < (c) < (a) (4) (b) < (d) < (a) < (c)

[AIEEE-2012]

Sol. (3)

(d) < (b) < (c) < (a) Acc. to (n + ) rule.

Q. If the kinetic energy of an electron is increased four times, the wavelength of the de-Broglie wave associated with it would become :-

(1) Two times

(2) Half

(3) One fourth

(4) Four time

[JEE-Main(online2012]

Sol. (2)

$\lambda \propto \frac{1}{\sqrt{\mathrm{KE}}}$

Q. The wave number of the first emission line in the Balmer series of H-Spectrum is :

(R = Rydberg constant) :

(1) $\frac{3}{4} \mathrm{R}$

(2) $\frac{9}{400} \mathrm{R}$

(3) $\frac{5}{36} \mathrm{R}$

(4) $\frac{7}{6} \mathrm{R}$

[JEE-Main(online) 2013]

Sol. (3)

$\bar{v}=\frac{1}{\mathrm{R}}\left(\frac{1}{2^{2}}-\frac{1}{3^{2}}\right)=\frac{5}{36 \mathrm{R}}$

Q. The de Broglie wavelength of a car of mass 1000 kg and velocity 36 km/hr is :

$\left(\mathrm{h}=6.63 \times 10^{-34} \mathrm{J} \mathrm{s}\right)$

(1) $6.626 \times 10^{-31} \mathrm{m}$

(2) $6.626 \times 10^{-34} \mathrm{m}$

(3) $6.626 \times 10^{-38} \mathrm{m}$

(4) $6.626 \times 10^{-30} \mathrm{m}$

[JEE-Main(online) 2013]

Sol. (3)

Q. For which of the following particles will it be most difficult to experimentally verify the de-Broglie relationship?

(1) a dust particle (2) an electron (3) a proton (4) an -particle.

[JEE-Main(online) 2014]

Sol. (1)

Q. If the binding energy of the electron in a hydrogen atom is 13.6 eV, the energy required to remove the electron from the first excited state of $\mathbf{L} \mathbf{i}^{++}$ is :

(1) 13.6 eV (2) 30.6 eV (3) 122.4 eV (4) 3.4 eV

[JEE-Main(online) 2014]

Sol. (2)

B.E. $=3.4 \times 9=30.6 \mathrm{eV}$

Q. Based on the equation

$\Delta \mathrm{E}=-2.0 \times 10^{-18} \mathrm{J}\left(\frac{1}{\mathrm{n}_{2}^{2}}-\frac{1}{\mathrm{n}_{1}^{2}}\right)$

the wavelength of the light that must be absorbed to excite hydrogen electron from level n = 1 to level n $=2$ will be $\left(\mathrm{h}=6.625 \times 10^{-34} \mathrm{Js}, \mathrm{C}=3 \times 10^{8} \mathrm{ms}^{-1}\right)$

(1) $2.650 \times 10^{-7} \mathrm{m}$

(2) $1.325 \times 10^{-7} \mathrm{m}$

(3) $1.325 \times 10^{-10} \mathrm{m}$

(4) $5.300 \times 10^{-10} \mathrm{m}$

[JEE-Main(online) 2014]

Sol. (2)

$\frac{1}{\lambda}=\frac{2 \times 10^{-18}}{\mathrm{hc}}\left[\frac{1}{(1)^{2}}-\frac{1}{(2)^{2}}\right]$

$\Rightarrow \frac{1}{\lambda}=\frac{2 \times 10^{-18}}{6.625 \times 10^{-34} \times 3 \times 10^{8}} \times \frac{3}{4}$

$\Rightarrow \lambda=\frac{2 \times 6.625 \times 10^{-34} \times 10^{8}}{10^{-18}}$

$=13.25 \times 10^{-8}$

$=1.325 \times 10^{-7} \mathrm{m}$

Q. If

be the threshold wavelength and wavelength of incident light, the velocity of photoelectron ejected from the metal surface is

[JEE-Main(online) 2014]

Sol. (1)

$\mathrm{E}=\phi+\frac{1}{2} \mathrm{mv}^{2}$

$\Rightarrow \frac{\mathrm{hc}}{\lambda}=\frac{\mathrm{hc}}{\lambda_{0}}+\frac{1}{2} \mathrm{mv}^{2}$

$\Rightarrow \mathrm{v}^{2}=\frac{2 \mathrm{hc}}{\mathrm{m}}\left[\frac{1}{\lambda}-\frac{1}{\lambda_{0}}\right] \Rightarrow \mathrm{v}=\sqrt{\frac{2 \mathrm{hc}}{\mathrm{m}}\left[\frac{1}{\lambda}-\frac{1}{\lambda_{0}}\right]}$

$\Rightarrow \mathrm{v}=\sqrt{\frac{2 \mathrm{hc}}{\mathrm{m}}\left[\frac{\lambda_{0}-\lambda}{\lambda \lambda_{0}}\right]}$

Q. Ionization energy of gaseous Na atoms is 495.5 $\mathrm{kjmol}^{-1}$ . The

lowest possible frequency of light that ionizes a sodium atom is

$\left(\mathrm{h}=6.626 \times 10^{-34} \mathrm{Js}, \mathrm{N}_{\mathrm{A}}=6.022 \times 10^{23} \mathrm{mol}^{-1}\right)$

(1) $3.15 \times 10^{15} \mathrm{s}^{-1}$

(2) $4.76 \times 10^{14} \mathrm{s}^{-1}$

(3) $1.24 \times 10^{15} \mathrm{s}^{-1}$

(4) $7.50 \times 10^{4} \mathrm{s}^{-1}$

[JEE-Main(online) 2014]

Sol. (3)

$\Delta \mathrm{E}=\mathrm{hv}$

$\mathrm{v}=\frac{\Delta \mathrm{E}}{\mathrm{h}}$

$\mathrm{v}=\frac{495.5 \times 10^{3} \mathrm{Joule}}{6.023 \times 10^{23}} \times \frac{1}{6.626 \times 10^{-34}}$

$\mathrm{v}=1.24 \times 10^{15} \mathrm{sec}^{-1}$

Q. Which of the following is the energy of a possible excited state of hydrogen?

(1) –3.4 eV (2) +6.8 eV (3) +13.6 eV (4) –6.8 eV

[JEE-Main(offline) 2015]

Sol. (1)

For H-atom, (Z = 1)

$\mathrm{E}_{\mathrm{n}}=-13.6 \times \frac{\mathrm{Z}^{2}}{\mathrm{n}^{2}} \mathrm{eV}$

\begin{aligned} \therefore \text { So for } \mathrm{E}_{1} &=-13.6 \mathrm{eV} \\ \mathrm{E}_{2} &=-3.4 \mathrm{eV} \end{aligned}

Q. A stream of electrons from a heated filament was passed between two charged plates kept at a potential difference V esu. If e and m are charge and mass of an electron respectively, then the value of $\mathrm{h} / \lambda$ (where $\lambda$is wavelength associated with electron wave) is given by :

(1) $\sqrt{2 \mathrm{meV}}$

(2) mev

(3) $2 \mathrm{meV}$

(4) $\sqrt{\mathrm{meV}}$

[JEE-Main 2016]

Sol. (1)

As electron of charge ‘e’ is passed through ‘V’ volt, kinetic energy of electron becomes = ‘eV’

As wavelength of $e^{-}$ wave = $(\lambda)=\frac{\mathrm{h}}{\sqrt{2 \mathrm{m} \cdot \mathrm{K} \cdot \mathrm{E}}}$

$\lambda=\frac{\mathrm{h}}{\sqrt{2 \mathrm{meV}}}$

$\therefore \quad \frac{\mathrm{h}}{\lambda}=\sqrt{2 \mathrm{meV}}$

Q. The radius of the second Bohr orbit for hydrogen atom is :

(Planks const. $\mathrm{h}=6.6262 \times 10^{-34} \mathrm{Js}$; mass of electron $=9.1091 \times 10^{-31} \mathrm{kg} ;$ charge of electron $\mathrm{e}=$ $1.60210 \times 10^{-19} \mathrm{C}:$ permittivity of vaccuml $\left.\epsilon_{0}=8.854185 \times 10^{-12} \mathrm{kg}^{-1} \mathrm{m}^{-3} \mathrm{A}^{2}\right)$

[JEE-Main 2017]

Sol. (4)

Radius of $\mathbf{n}^{\mathrm{th}}$ Bohr orbit in H-atom

Radius of II Bohr orbit $=0.53 \times(2)^{2}$