Chemical & Ionic Equilibrium · JEE Main previous year questions

Value of $K_P$ for the equilibrium reaction ${\mathrm{N}}_2{\mathrm{O}}_{4(\mathrm{g})}\rightleftharpoons 2N{\mathrm{O}}_{2(\mathrm{g})}$ at 288 K is 47.9. The $K_C$ for this reaction at same temperature is ____. (Nearest integer) (R = 0.083 L bar ${\mathrm{K}}^{-1}\mathrm{mo}{\mathrm{l}}^{-1}$)

$2{\text{SO}}_2(\text{g})+{\text{O}}_2(\text{g})\rightleftharpoons 2{\text{SO}}_3(\text{g})$ In an equilibrium mixture, the partial pressures are ${\text{P}}_{{\text{SO}}_3}=43\text{ kPa}$; ${\text{P}}_{{\text{O}}_2}=530\text{ Pa}$ and ${\text{P}}_{{\text{SO}}_2}=45\text{ kPa}$. The equilibrium constant ${\text{K}}_p=$ ________ $\times 10^{-2}$. (Nearest integer)

1. A.
2. B.
3. C.
4. D.

Given below are two statements : One is labelled as Assertion A and the other labelled as reason R Assertion A : During the boiling of water having temporary hardness, $\mathrm{Mg}(\mathrm{HC}{\mathrm{O}}_3{)}_2$ is converted to $\mathrm{MgC}{\mathrm{O}}_3$. Reason R : The solubility product of $\mathrm{Mg}(\mathrm{OH}{)}_2$ is greater than that of $\mathrm{MgC}{\mathrm{O}}_3$. In the light of the above statements, choose the most appropriate answer from the options given below :

1. A.Both A and R are true but R is not the correct explanation of A
2. B.A is true but R is false
3. C.Both A and R are true and R is the correct explanation of A
4. D.A is false but R is true

In order to prepare a buffer solution of pH 5.74, sodium acetate is added to acetic acid. If the concentration of acetic acid in the buffer is 1.0 M, the concentration of sodium acetate in the buffer is ___________ M. (Round off to the Nearest Integer). [Given : pKa (acetic acid) = 4.74]

Given below are two statements : Statement I : ${\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}$ and $\mathrm{AgCN}$ both can generate nucleophile. Statement II : $\mathrm{KCN}$ and $\mathrm{AgCN}$ both will generate nitrile nucleophile with all reaction conditions. Choose the most appropriate option :

1. A.Statement I is false but statement II is true.
2. B.Both statement I and statement II are true.
3. C.Both statement I and statement II are false.
4. D.Statement I is true but statement II is false.

The gas phase reaction $2\mathrm{A}(g)\rightleftharpoons {\mathrm{A}}_2(g)$ at $400\mathrm{K}$ has $\Delta {\mathrm{G}}^{\circ }=+25.2\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$. The equilibrium constant ${\mathrm{K}}_{\mathrm{C}}$ for this reaction is ____ $\times 10^{-2}$. (Round off to the Nearest Integer). [Use : $\mathrm{R}=8.3\mathrm{J}\mathrm{mo}{\mathrm{l}}^{-1}{\mathrm{K}}^{-1}$, $\ln 10=2.3$, ${\log }_{10}2=0.30$, $1\mathrm{atm}=1\mathrm{bar}$] $[\mathrm{antilog}(-0.3)=0.501]$

Two salts ${\mathrm{A}}_2\mathrm{X}$ and $\mathrm{MX}$ have the same value of solubility product of $4.0\times 10^{-12}$. The ratio of their molar solubilities i.e. $\frac{S({\mathrm{A}}_2\mathrm{X})}{S(\mathrm{MX})}=$ _______. (Round off to the Nearest Integer)

For the reaction $A(g)\rightleftharpoons B(g)$ at $495\text{ K}$, ${\Delta }_{\mathrm{r}}{G}^{\circ }=-9.478{\text{ kJ mol}}^{-1}$. If we start the reaction in a closed container at $495\text{ K}$ with 22 millimoles of A, the amount of B in the equilibrium mixture is _______ millimoles. (Round off to the Nearest Integer). $[R=8.314{\text{ J mol}}^{-1}{\text{ K}}^{-1}$; $\ln 10=2.303]$

A homogeneous ideal gaseous reaction $A{B}_{2(g)}\rightleftharpoons A_{(g)}+2B_{(g)}$ is carried out in a 25 litre flask at $27^{\circ }\mathrm{C}$. The initial amount of $\mathrm{A}{\mathrm{B}}_2$ was 1 mole and the equilibrium pressure was 1.9 atm. The value of ${\mathrm{K}}_{\mathrm{p}}$ is $x\times 10^{-2}$. The value of x is _________. (Integer answer) $[R=0.08206\mathrm{d}{\mathrm{m}}^3\mathrm{atm}{\mathrm{K}}^{-1}\mathrm{mo}{\mathrm{l}}^{-1}]$

The pH of ammonium phosphate solution, if $\mathrm{p}{\mathrm{k}}_{\mathrm{a}}$ of phosphoric acid and $\mathrm{p}{\mathrm{k}}_{\mathrm{b}}$ of ammonium hydroxide are 5.23 and 4.75 respectively, is _________. (Nearest integer)

The solubility of $\mathrm{Ca}(\mathrm{OH}{)}_2$ in water is : $[\text{Given : The solubility product of }\mathrm{Ca}(\mathrm{OH}{)}_2\text{ in water}=5.5\times 10^{-6}]$

1. A.$1.11\times 10^{-6}$
2. B.$1.11\times 10^{-2}$
3. C.$1.77\times 10^{-6}$
4. D.$1.77\times 10^{-2}$

Given below are two statements : Statement I : The pH of rain water is normally 5.6. Statement II : If the pH of rain water drops below 5.6, it is called acid rain. In the light of the above statements, choose the correct answer from the options given below :

1. A.Both Statement I and Statement II are true.
2. B.Both Statement I and Statement II are false.
3. C.Statement I is true but Statement II is false.
4. D.Statement I is false but Statement II is true.

Arrange the following solutions in the decreasing order of pOH : (A) $0.01\text{ M }\mathrm{HCl}$ (B) $0.01\text{ M }\mathrm{NaOH}$ (C) $0.01\text{ M }\mathrm{C}{\mathrm{H}}_3\mathrm{COONa}$ (D) $0.01\text{ M }\mathrm{NaCl}$

1. A.$\text{(B)}>\text{(C)}>\text{(D)}>\text{(A)}$
2. B.$\text{(A)}>\text{(D)}>\text{(C)}>\text{(B)}$
3. C.$\text{(A)}>\text{(C)}>\text{(D)}>\text{(B)}$
4. D.$\text{(B)}>\text{(D)}>\text{(C)}>\text{(A)}$

For the reaction $$\mathrm{F}{\mathrm{e}}_2\mathrm{N}(\mathrm{s})+\frac{3}{2}{\mathrm{H}}_2(\mathrm{g})\rightleftharpoons 2\mathrm{Fe}(\mathrm{s})+\mathrm{N}{\mathrm{H}}_3(\mathrm{g})$$ the correct relation between $K_C$ and $K_p$ is :

1. A.$K_C=K_p(RT{)}^{1/2}$
2. B.$K_C=K_p(RT{)}^{-1/2}$
3. C.$K_C=K_p(RT)$
4. D.$K_C=K_p(RT{)}^{3/2}$

The variation of equilibrium constant with temperature is given below : | Temperature | Equilibrium Constant | | :--- | :--- | | $T_1=25^{\circ }\mathrm{C}$ | $K_1=10$ | | $T_2=100^{\circ }\mathrm{C}$ | $K_2=100$ | The values of $\Delta H^{\circ }$, $\Delta G^{\circ }$ at $T_1$ and $\Delta G^{\circ }$ at $T_2$ (in $\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$) respectively, are close to : $[\text{Use }R=8.314\mathrm{J}{\mathrm{K}}^{-1}\mathrm{mo}{\mathrm{l}}^{-1}]$

1. A.$28.4$, $-5.71$ and $-14.29$
2. B.$0.64$, $-7.14$ and $-5.71$
3. C.$28.4$, $-7.14$ and $-5.71$
4. D.$0.64$, $-5.71$ and $-14.29$

The value of $K_C$ is 64 at 800 K for the reaction $${\mathrm{N}}_2(\mathrm{g})+3{\mathrm{H}}_2(\mathrm{g})\rightleftharpoons 2N{\mathrm{H}}_3(\mathrm{g})$$ The value of $K_C$ for the following reaction is : $$\mathrm{N}{\mathrm{H}}_3(\mathrm{g})\rightleftharpoons \frac{1}{2}{\mathrm{N}}_2(\mathrm{g})+\frac{3}{2}{\mathrm{H}}_2(\mathrm{g})$$

1. A.8
2. B.$\frac{1}{8}$
3. C.$\frac{1}{4}$
4. D.$\frac{1}{64}$

If the solubility product of $\mathrm{A}{\mathrm{B}}_2$ is $3.20\times 10^{-11}{\mathrm{M}}^3$, then the solubility of $\mathrm{A}{\mathrm{B}}_2$ in pure water is ______ $\times 10^{-4}\mathrm{mol}{\mathrm{L}}^{-1}$. [Assuming that neither kind of ion reacts with water]

An acidic buffer is obtained on mixing :

1. A.100 mL of 0.1 M HCl and 200 mL of $0.1\mathrm{M}\mathrm{C}{\mathrm{H}}_3\mathrm{COONa}$
2. B.100 mL of 0.1 M HCl and 200 mL of 0.1 M NaCl
3. C.100 mL of $0.1\mathrm{M}\mathrm{C}{\mathrm{H}}_3\mathrm{COOH}$ and 100 mL of 0.1 M NaOH
4. D.100 mL of $0.1\mathrm{M}\mathrm{C}{\mathrm{H}}_3\mathrm{COOH}$ and 200 mL of 0.1 M NaOH

1. A.
2. B.
3. C.
4. D.

For the following Assertion and Reason, the correct option is Assertion (A): When $\mathrm{Cu}(\mathrm{II})$ and sulphide ions are mixed, they react together extremely quickly to give a solid. Reason (R): The equilibrium constant of $\mathrm{C}{\mathrm{u}}^{2+}(\mathrm{aq})+{\mathrm{S}}^{2-}(\mathrm{aq})\rightleftharpoons \mathrm{CuS}(\mathrm{s})$ is high because the solubility product is low.

1. A.(A) is false and (R) is true.
2. B.Both (A) and (R) are true but (R) is not the explanation for (A).
3. C.Both (A) and (R) are true and (R) is the explanation for (A).
4. D.Both (A) and (R) are false.

For the disproportionation reaction $2\mathrm{C}{\mathrm{u}}^{+}(\mathrm{aq})\rightleftharpoons \mathrm{Cu}(\mathrm{s})+\mathrm{C}{\mathrm{u}}^{2+}(\mathrm{aq})$ at 298 K. $\ln K$ (where K is the equilibrium constant) is _______ $\times 10^{-1}$. Given : $(E_{\mathrm{C}{\mathrm{u}}^{2+}/C{\mathrm{u}}^{+}}^{\circ }=0.16\mathrm{V}$ $E_{\mathrm{C}{\mathrm{u}}^{+}/Cu}^{\circ }=0.52\mathrm{V}$ $\frac{RT}{F}=0.025)$

The ${\mathrm{K}}_{\mathrm{sp}}$ for the following dissociation is $1.6\times 10^{-5}$ $$\mathrm{PbC}{\mathrm{l}}_{2(\mathrm{s})}\leftrightharpoons \mathrm{P}{\mathrm{b}}_{(\mathrm{aq})}^{2+}+2C{\mathrm{l}}_{(\mathrm{aq})}^{-}$$ Which of the following choices is correct for a mixture of 300 mL 0.134 M $\mathrm{Pb}(\mathrm{N}{\mathrm{O}}_3{)}_2$ and 100 mL 0.4 M $\mathrm{NaCl}$ ?

1. A.$\mathrm{Q}>{\mathrm{K}}_{\mathrm{sp}}$
2. B.Not enough data provided
3. C.$\mathrm{Q}<{\mathrm{K}}_{\mathrm{sp}}$
4. D.$\mathrm{Q}={\mathrm{K}}_{\mathrm{sp}}$

1. A.$>1400{}^{\circ }\mathrm{C}$
2. B.$>1200{}^{\circ }\mathrm{C}\text{ but }<1400{}^{\circ }\mathrm{C}$
3. C.$<1400{}^{\circ }\mathrm{C}$
4. D.$<1200{}^{\circ }\mathrm{C}$

1. A.1
2. B.2
3. C.8
4. D.4