Ionic Equilibrium – JEE Main Previous Year Questions with Solutions

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

 

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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}

\mathrm{pH}=3 \quad ;\left[\mathrm{H}^{+}\right]=10^{-3}=\mathrm{C}_{0} \alpha

\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)


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Comments
  • May 28, 2020 at 9:51 am

    here in one of the ques. of jee 2013 options are incorrect
    not only in this chap. but in all other chap there are sone quest. which are either incomplete or wrong options are given
    also there is overlapping of texts😡

    quest. are good🤘

  • May 9, 2020 at 10:56 am

    Good questions

  • April 3, 2020 at 7:03 pm

    ThanQ
    Very useful material……!!!..