eSaral - JEE | NEET | Class 8-10 Exam Prep App

In thermodynamics, heat and work are :

Question: In thermodynamics, heat and work are :Path functionsIntensive thermodynamic state variablesIntensive thermodynamic state variablesPoint functionsCorrect Option: 1 Solution: (1) Heat and work are treated as path functions in thermodynamics. $\Delta \mathrm{Q}=\Delta \mathrm{U}+\Delta \mathrm{W}$ Since work done by gas depends on type of process i.e. path and $\Delta U$ depends just on initial and final states, so $\Delta Q$ i.e. heat, also has to depend on process is path....

Write the mechanism of hydration of ethene to yield ethanol.

Question: Write the mechanism of hydration of ethene to yield ethanol. Solution: The mechanism of hydration of ethene to form ethanol involves three steps. Step 1: Protonation of ethene to form carbocation by electrophilic attack of H3O+: Step 2: Nucleophilic attack of water on carbocation: Step 3: Deprotonation to form ethanol:...

A metallic sphere 1 dm in diameter is beaten into

Question: A metallic sphere 1 dm in diameter is beaten into a circular sheet of uniform thickness equal to 1 mm. Find the radius of the sheet. Solution: Radius of metallic sphere $r=\frac{10}{2} \mathrm{~cm}$ Thickness of circular sheet $h=1 \mathrm{~mm}$ $=\frac{1}{10} \mathrm{~cm}$ Letr1be the radius of sheet. Therefore, Volume of circular sheet = volume of metallic sphere $r_{1}^{2} \times \frac{1}{10}=\frac{4}{3} \times(5)^{3}$ $r_{1}^{2}=\frac{4 \times 125 \times 10}{3}$ $=\frac{5000}{3}$ $...

In an isosceles ∆ABC, if AC = BC and AB2 = 2AC2, then ∠C = ?

Question: In an isosceles ∆ABC,ifAC=BCandAB2= 2AC2, then C= ?(a) 30(b) 45(c) 60(d) 90 Solution: (d) 90Given:AC = BC $A B^{2}=2 A C^{2}=A C^{2}+A C^{2}=A C^{2}+B C^{2}$ Applying Pythagoras theorem, we conclude that∆ABCis right angled at C. or, $\angle C=90^{\circ}$...

Write chemical reaction for the preparation of phenol from chlorobenzene.

Question: Write chemical reaction for the preparation of phenol from chlorobenzene. Solution: Chlorobenzene is fused with NaOH (at 623 K and 320 atm pressure) to produce sodium phenoxide, which gives phenol on acidification....

In the given figure, O is the point of intersection of two chords AB and CD such

Question: In the given figure,Ois the point of intersection of two chordsABandCDsuch thatOB=ODand AOC= 45. Then, ∆OACand ∆ODBare (a) equilateral and similar(b) equilateral but not similar(c) isosceles and similar(d) isosceles but not similar Solution: (c) isosceles and similarIn ∆AOC and ∆ODB, we have: $\angle A O C=\angle D O B \quad$ (Vertically opposite angles) and $\angle O A C=\angle O D B \quad$ (Angles in the same segment) Therefore, by AA similarity theorem, we conclude that $\triangle A...

Starting at temperature 300 K,

Question: Starting at temperature $300 \mathrm{~K}$, one mole of an ideal diatomic gas $(\gamma=1.4)$ is first compressed adiabatically from volume $\mathrm{V}_{1}$ to $\mathrm{V}_{2}=\frac{\mathrm{V}_{1}}{16}$. It is then allowed to expand isobarically to volume $2 \mathrm{~V}_{2}$. If all the processes are the quasi-static then the final temperature of the gas (in ${ }^{\circ} \mathrm{K}$ ) is (to the nearest integer)__________ Solution: (1818) For an adiabatic process, $\mathrm{TV} \gamma^{-1...

Solve this

Question: If $\Delta A B C \sim \Delta Q R P, \frac{\operatorname{ar}(\Delta A B C)}{\operatorname{ar}(\Delta P Q R)}=\frac{9}{4}, A B=18 \mathrm{~cm}$ and $B C=15 \mathrm{~cm}$, then $P \mathrm{R}=?$ (a) 8 cm(b) 10 cm(c) 12 cm (d) $\frac{20}{3} \mathrm{~cm}$ Solution: (b) 10 cm $\because \triangle A B C \sim \triangle Q R P$ $\therefore \frac{A B}{Q R}=\frac{B C}{P R}$ Now, $\frac{\operatorname{ar}(\triangle A B C)}{\operatorname{ar}(\triangle Q R P)}=\frac{9}{4}$ $\Rightarrow\left(\frac{A B}{Q...

Give the equations of reactions for the preparation of phenol from cumene.

Question: Give the equations of reactions for the preparation of phenol from cumene. Solution: To prepare phenol, cumene is first oxidized in the presence of air of cumene hydro-peroxide. Then, cumene hydroxide is treated with dilute acid to prepare phenol and acetone as by-products....

While separating a mixture of ortho and para nitrophenols by steam distillation,

Question: While separating a mixture oforthoandparanitrophenols by steam distillation, name the isomer which will be steam volatile. Give reason. Solution: Intramolecular H-bonding is present ino-nitrophenol. Inp-nitrophenol, the molecules are strongly associated due to the presence of intermolecular bonding. Hence,o-nitrophenol is steam volatile....

Give the structures and IUPAC names of monohydric phenols of molecular formula,

Question: Give the structures and IUPAC names of monohydric phenols of molecular formula, C7H8O. Solution:...

The line segments joining the midpoints of the sides of a triangle form four triangles, each of which is

Question: The line segments joining the midpoints of the sides of a triangle form four triangles, each of which is(a) congruent to the original triangle(b) similar to the original triangle(c) an isosceles triangle(d) an equilateral triangle Solution: (b) similar to the original triangleThe line segments joining the midpoints of the sides of a triangle form four triangles, each of which is similar to the original triangle....

What is meant by hydroboration-oxidation reaction?

Question: What is meant by hydroboration-oxidation reaction? Illustrate it with an example. Solution: The addition of borane followed by oxidation is known as the hydroboration-oxidation reaction. For example, propan-1-ol is produced by the hydroboration-oxidation reaction of propene. In this reaction, propene reacts with diborane (BH3)2to form trialkyl borane as an addition product. This addition product is oxidized to alcohol by hydrogen peroxide in the presence of aqueous sodium hydroxide....

A milk container is made of metal sheet in the shape of frustum

Question: A milk container is made of metal sheet in the shape of frustum of cone whose volume is $10459 \frac{3}{7} \mathrm{~cm}^{3}$. The radii of its lower and upper circular ends are $8 \mathrm{~cm}$ and $20 \mathrm{~cm}$ respectively. Find the cost of metal sheet used in making the container at the rate of Rs. $1.40$ per $\mathrm{cm}^{2}$. (Use $\pi=22 / 7$ ) Solution: Let the depth of the container ishcm. The radii of the top and bottom circles of the container arer1=20cm andr2=8cm respect...

Alcohols are comparatively more soluble in water than hydrocarbons of comparable molecular masses.

Question: Alcohols are comparatively more soluble in water than hydrocarbons of comparable molecular masses. Explain this fact. Solution: Alcohols form H-bonds with water due to the presence of OH group. However, hydrocarbons cannot form H-bonds with water. As a result, alcohols are comparatively more soluble in water than hydrocarbons of comparable molecular masses....

Two isosceles triangles have their corresponding angles equal and their areas are in the ratio 25 : 36.

Question: Two isosceles triangles have their corresponding angles equal and their areas are in the ratio 25 : 36. The ratio of their corresponding heights is(a) 25 : 36(b) 36 : 25(c) 5 : 6(d) 6 : 5 Solution: (c) 5:6Letxandybe the corresponding heights of the two triangles.It is given that the corresponding angles of the triangles are equal.Therefore, the triangles are similar. (By AA criterion)Hence, $\frac{\operatorname{ar}\left(\triangle_{1}\right)}{\operatorname{ar}\left(\triangle_{2}\right)}...

Explain why propanol has higher boiling point than that of the hydrocarbon,

Question: Explain why propanol has higher boiling point than that of the hydrocarbon, butane? Solution: Propanol undergoes intermolecular H-bonding because of the presence of OH group. On the other hand, butane does not Therefore, extra energy is required to break hydrogen bonds. For this reason, propanol has a higher boiling point than hydrocarbon butane....

Which of the following is an equivalent cyclic process corresponding to the thermodynamic cyclic given in the figure?

Question: Which of the following is an equivalent cyclic process corresponding to the thermodynamic cyclic given in the figure? where, $1 \rightarrow 2$ is adiabatic. (Graphs are schematic and are not to scale) Correct Option: , 3 Solution: (3) For process $3 \rightarrow 1$ volume is constant $\therefore \quad$ Graph given in option (4) is wrong. And process $1 \rightarrow 2$ is adiabatic $\therefore$ graph in option (1) is wrong $\because \quad v=$ constant $P \uparrow, T \uparrow$ For Process ...

∆ABC ∼ ∆DEF such that ar(∆ABC) = 36 cm2 and ar(∆DEF) = 49 cm2.

Question: ∆ABC ∆DEFsuch that ar(∆ABC) = 36 cm2and ar(∆DEF) = 49 cm2.Then, the ratio of their corresponding sides is(a) 36 : 49(b) 6 : 7(c) 7 : 6 (d) $\sqrt{6}: \sqrt{7}$ Solution: (b) 6:7∵∆ABC ∆DEF $\therefore \frac{A B}{D E}=\frac{B C}{E F}=\frac{A C}{D F} \quad \ldots(\mathrm{i})$ Also, $\frac{\operatorname{ar}(\triangle A B C)}{a r(\triangle D E F)}=\frac{A B^{2}}{D E^{2}}$ $\Rightarrow \frac{36}{49}=\frac{A B^{2}}{D E^{2}}$ $\Rightarrow \frac{6}{7}=\frac{A B}{D E}$ $\Rightarrow \frac{A B}{D ...

A bucket open at the top,

Question: A bucket open at the top, and made up of a metal sheet is in the form of a frustum of a cone. The depth of the bucket is 24 cm and the diameters of its upper and lower circular ends are 30 cm and 10 cm respectively. Find the cost of metal sheet used in it at the rate of Rs. 10 per 100 cm2.(Use = 3.14). Solution: The slant height of the bucket is given by $l=\sqrt{h^{2}+(R-r)^{2}}$ $=\sqrt{(24)^{2}+(15-5)^{2}}$ $=\sqrt{576+100}$ $=\sqrt{676}$ $=26 \mathrm{~cm}$ Surface area of bucket = ...

Solve the following

Question: (i)Draw the structures of all isomeric alcohols of molecular formula C5H12O and give their IUPAC names. (ii)Classify the isomers of alcohols in question 11.3 (i) as primary, secondary and tertiary alcohols. Solution: (i)The structures of all isomeric alcohols of molecular formula, C5H12O are shown below: (a) Pentan-1-ol (1) (b) 2-Methylbutan-1-ol (1) (c) 3-Methylbutan-1-ol (1) (d) 2, 2-Dimethylpropan-1-ol (1) (e) Pentan-2-ol (2) (f) 3-Methylbutan-2-ol (2) (g) Pentan-3-ol (2) (h) 2-Meth...

Write structures of the compounds whose IUPAC names are as follows:

Question: Write structures of the compounds whose IUPAC names are as follows: (i)2-Methylbutan-2-ol (ii)1-Phenylpropan-2-ol (iii)3,5-Dimethylhexane 1, 3, 5-triol (iv)2,3 Diethylphenol (v)1 Ethoxypropane (vi)2-Ethoxy-3-methylpentane (vii)Cyclohexylmethanol (viii)3-Cyclohexylpentan-3-ol (ix)Cyclopent-3-en-1-ol (x)3-Chloromethylpentan-1-ol. Solution: (i) (ii) (iii) (iv) (v) (vi) (vii) (viii) (ix) (x)...

In ∆ABC and ∆DEF, we have:

Question: In $\triangle A B C$ and $\Delta D E F$, we have: $\frac{A B}{D E}=\frac{B C}{E F}=\frac{A C}{D F}=\frac{5}{7}$, then ar(∆ABC) : ar(∆DEF) = ? (a) 5 : 7(b) 25 : 49(c) 49 : 25(d) 125 : 343 Solution: (b) 25 : 49 - In $\triangle \mathrm{ABC}$ and $\triangle \mathrm{DEF}$, we have : $\frac{A B}{D E}=\frac{B C}{E F}=\frac{A C}{D F}=\frac{5}{7}$ Therefore, by SSS criterion, we conclude that $\triangle A B C \sim \triangle D E F$. $\Rightarrow \frac{\operatorname{ar}(\triangle A B C)}{\operato...

Write IUPAC names of the following compounds:

Question: Write IUPAC names of the following compounds: (i) (ii) (iii) (iv) (v) (vi) (vii) (viii) (ix) (x) (xi) (xii) Solution: (i)2, 2, 4-Trimethylpentan-3-ol (ii)5-Ethylheptane-2, 4-diol (iii)Butane-2, 3-diol (iv)Propane-1, 2, 3-triol (v)2-Methylphenol (vi)4-Methylphenol (vii)2, 5-Dimethylphenol (viii)2, 6-Dimethylphenol (ix)1-Methoxy-2-methylpropane (x)Ethoxybenzene (xi)1-Phenoxyheptane (xii)2-Ethoxybutane...

A solid cone of base radius 10 cm is cut into two parts

Question: A solid cone of base radius 10 cm is cut into two parts through the mid-point of its height, by a plane parallel to its base. Find the ratio in the volumes of two parts of the cone. Solution: Let the height of the cone beH.Now, the cone is divided into two parts by the parallel plane OC = CAH2 Now, In ∆OCD and OAB OCD = OAB (Corresponding angles) ODC = OBA (Corresponding angles) By AA-similarity criterion ∆OCD ∆OAB $\therefore \frac{\mathrm{CD}}{\mathrm{AB}}=\frac{\mathrm{OC}}{\mathrm{...

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