Chemical & Ionic Equilibrium · JEE Main previous year questions

1. A.Malonic acid
2. B.Oxalic acid
3. C.Succinic acid
4. D.Gluconic acid

For a certain reaction at $300\text{ K}$, $\mathrm{K}=10$, then $\Delta {\mathrm{G}}^{\circ }$ for the same reaction is - ________ $\times 10^{-1}{\text{ kJ mol}}^{-1}$. (Given $\mathrm{R}=8.314\mathrm{J}{\mathrm{K}}^{-1}\mathrm{mo}{\mathrm{l}}^{-1}$ )

Consider the following redox reaction : $$\mathrm{Mn}{\mathrm{O}}_4^{-}+{\mathrm{H}}^{+}+{\mathrm{H}}_2{\mathrm{C}}_2{\mathrm{O}}_4\rightleftharpoons \mathrm{M}{\mathrm{n}}^{2+}+{\mathrm{H}}_2\mathrm{O}+\mathrm{C}{\mathrm{O}}_2$$ The standard reduction potentials are given as below $\left({\mathrm{E}}_{\mathrm{red}}^0\right)$ : ${\mathrm{E}}_{\mathrm{Mn}{\mathrm{O}}_4^{-}/M{\mathrm{n}}^{2+}}^{\circ }=+1.51\text{ V}$ ${\mathrm{E}}_{\mathrm{C}{\mathrm{O}}_2/{\mathrm{H}}_2{\mathrm{C}}_2{\mathrm{O}}_4}^{\circ }=-0.49\text{ V}$ If the equilibrium constant of the above reaction is given as ${\mathrm{K}}_{\mathrm{eq}}=10^x$, then the value of $x=$ ________ (nearest integer)

For the given reaction, choose the correct expression of ${\mathrm{K}}_{\mathrm{C}}$ from the following :- $\mathrm{F}{\mathrm{e}}_{(\mathrm{aq})}^{3+}+\mathrm{SC}{\mathrm{N}}_{(\mathrm{aq})}^{-}\rightleftharpoons (\mathrm{FeSCN}{)}_{(\mathrm{aq})}^{2+}$

1. A.${\mathrm{K}}_{\mathrm{C}}=\frac{[\mathrm{F}{\mathrm{e}}^{3+}][\mathrm{SC}{\mathrm{N}}^{-}]}{[\mathrm{FeSC}{\mathrm{N}}^{2+}]}$
2. B.${\mathrm{K}}_{\mathrm{C}}=\frac{[\mathrm{FeSC}{\mathrm{N}}^{2+}]}{[\mathrm{F}{\mathrm{e}}^{3+}][\mathrm{SC}{\mathrm{N}}^{-}]}$
3. C.${\mathrm{K}}_{\mathrm{C}}=\frac{[\mathrm{FeSC}{\mathrm{N}}^{2+}{]}^2}{[\mathrm{F}{\mathrm{e}}^{3+}][\mathrm{SC}{\mathrm{N}}^{-}]}$
4. D.${\mathrm{K}}_{\mathrm{C}}=\frac{[\mathrm{FeSC}{\mathrm{N}}^{2+}]}{[\mathrm{F}{\mathrm{e}}^{3+}{]}^2[\mathrm{SC}{\mathrm{N}}^{-}{]}^2}$

Consider the following reaction at $298\mathrm{K}$: $\frac{3}{2}{\mathrm{O}}_{2(\mathrm{g})}\rightleftharpoons {\mathrm{O}}_{3(\mathrm{g})};{\mathrm{K}}_{\mathrm{P}}=2.47\times 10^{-29}$. ${\Delta }_r{G}^{\ominus }$ for the reaction is ____ $\mathrm{kJ}$. (Given $\mathrm{R}=8.314\mathrm{J}{\mathrm{K}}^{-1}\mathrm{mo}{\mathrm{l}}^{-1}$)

${\mathrm{A}}_{(\mathrm{g})}\rightleftharpoons {\mathrm{B}}_{(\mathrm{g})}+\frac{\mathrm{C}}{2}(\mathrm{g})$ The correct relationship between ${\mathrm{K}}_{\mathrm{P}},\alpha$ and equilibrium pressure $\mathrm{P}$ is

1. A.$K_P=\frac{{\alpha }^{1/2}{P}^{3/2}}{(2+\alpha {)}^{3/2}}$
2. B.$K_P=\frac{{\alpha }^{3/2}{P}^{1/2}}{(2+\alpha {)}^{1/2}(1-\alpha )}$
3. C.$K_P=\frac{{\alpha }^{1/2}{P}^{1/2}}{(2+\alpha {)}^{3/2}}$
4. D.$K_P=\frac{{\alpha }^{1/2}{P}^{1/2}}{(2+\alpha {)}^{1/2}}$

Given below are two statements: Statement I : Group 13 trivalent halides get easily hydrolyzed by water due to their covalent nature. Statement II : $\mathrm{AlC}{\mathrm{l}}_3$ upon hydrolysis in acidified aqueous solution forms octahedral $[\mathrm{Al}({\mathrm{H}}_2\mathrm{O}{)}_6{]}^{3+}$ ion. In the light of the above statements, choose the correct answer from the options given below :

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 pH at which $\mathrm{Mg}(\mathrm{OH}{)}_2[{\mathrm{K}}_{\mathrm{sp}}=1\times 10^{-11}]$ begins to precipitate from a solution containing $0.10\text{ M}\mathrm{M}{\mathrm{g}}^{2+}$ ions is _________.

For the reaction ${\mathrm{N}}_2{\mathrm{O}}_{4(\mathrm{g})}\rightleftharpoons 2N{\mathrm{O}}_{2(\mathrm{g})}$, ${\mathrm{K}}_{\mathrm{p}}=0.492\text{ atm}$ at $300\text{ K}$. ${\mathrm{K}}_{\mathrm{c}}$ for the reaction at same temperature is _________ $\times 10^{-2}$. (Given : $\mathrm{R}=0.082{\text{ L atm mol}}^{-1}{\text{ K}}^{-1}$)

The following concentrations were observed at $500\text{ K}$ for the formation of $\mathrm{N}{\mathrm{H}}_3$ from ${\mathrm{N}}_2$ and ${\mathrm{H}}_2$. At equilibrium ; $[{\mathrm{N}}_2]=2\times 10^{-2}\mathrm{M}$, $[{\mathrm{H}}_2]=3\times 10^{-2}\mathrm{M}$ and $[\mathrm{N}{\mathrm{H}}_3]=1.5\times 10^{-2}\mathrm{M}$. Equilibrium constant for the reaction is _________.

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

Given below are two statements : Statement (I) : Aqueous solution of ammonium carbonate is basic. Statement (II) : Acidic/basic nature of salt solution of a salt of weak acid and weak base depends on $K_a$ and $K_b$ value of acid and the base forming it. In the light of the above statements, choose the most appropriate answer from the options given below :

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

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

The hydrogen electrode is dipped in a solution of $\text{pH}=3$ at $25^{\circ }\text{C}$. The potential of the electrode will be $-$ _______ $\times 10^{-2}\text{ V}$. $\left(\frac{2.303\text{RT}}{\text{F}}=0.059\text{ V}\right)$

$25.0\text{ mL}$ of $0.050\text{ M}$ $\mathrm{Ba}(\mathrm{N}{\mathrm{O}}_3{)}_2$ is mixed with $25.0\text{ mL}$ of $0.020\text{ M}$ $\mathrm{NaF}$. ${\mathrm{K}}_{sp}$ of ${\mathrm{BaF}}_2$ is $0.5\times 10^{-6}$ at $298\text{ K}$. The ratio of $[{\mathrm{Ba}}^{2+}][{\mathrm{F}}^{-}{]}^2$ and ${\mathrm{K}}_{sp}$ is ___________. (Nearest integer)

At $298\mathrm{K}$, the standard reduction potential for $\mathrm{C}{\mathrm{u}}^{2+}/Cu$ electrode is $0.34\mathrm{V}$. Given : ${\mathrm{K}}_{\mathrm{sp}}\mathrm{Cu}(\mathrm{OH}{)}_2=1\times 10^{-20}$ Take $\frac{2.303\mathrm{RT}}{\mathrm{F}}=0.059\mathrm{V}$ The reduction potential at $\mathrm{pH}=14$ for the above couple is $(-)x\times 10^{-2}\mathrm{V}$. The value of $x$ is ____

$20\mathrm{mL}$ of $0.1\mathrm{M}\mathrm{NaOH}$ is added to $50\mathrm{mL}$ of $0.1\mathrm{M}$ acetic acid solution. The $\mathrm{pH}$ of the resulting solution is ____ $\times 10^{-2}$ (Nearest integer) Given : $\mathrm{pKa}(\mathrm{C}{\mathrm{H}}_3\mathrm{COOH})=4.76$ $\log 2=0.30$ $\log 3=0.48$

An analyst wants to convert $1\text{ L}$ $\mathrm{HCl}$ of $\mathrm{pH}=1$ to a solution of $\mathrm{HCl}$ of $\mathrm{pH}2$. The volume of water needed to do this dilution is __________ mL. (Nearest integer)

A mixture of $1\text{ mole}$ of ${\mathrm{H}}_2\mathrm{O}$ and $1\text{ mole}$ of $\mathrm{CO}$ is taken in a $10\text{ litre}$ container and heated to $725\text{ K}$. At equilibrium $40\%$ of water by mass reacts with carbon monoxide according to the equation : $$\mathrm{CO}(g)+{\mathrm{H}}_2\mathrm{O}(g)\rightleftharpoons \mathrm{C}{\mathrm{O}}_2(g)+{\mathrm{H}}_2(g)$$ The equilibrium constant ${\mathrm{K}}_{\mathrm{c}}\times 10^2$ for the reaction is _________. (Nearest integer)

The number of correct statement/s involving equilibria in physical processes from the following is ________ (A) Equilibrium is possible only in a closed system at a given temperature. (B) Both the opposing processes occur at the same rate. (C) When equilibrium is attained at a given temperature, the value of all its parameters became equal. (D) For dissolution of solids in liquids, the solubility is constant at a given temperature.

The difference in the oxidation state of $\text{Xe}$ between the oxidised product of $\text{Xe}$ formed on complete hydrolysis of ${\text{XeF}}_4$ and ${\text{XeF}}_4$ is _________

1. A.A-III, B-I, C-IV, D-II
2. B.A-III, B-I, C-II, D-IV
3. C.A-IV, B-III, C-II, D-I
4. D.A-I, B-III, C-IV, D-II

A compound 'X' when treated with phthalic anhydride in presence of concentrated ${\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$ yields 'Y'. 'Y' is used as an acid/base indicator. 'X' and 'Y' are respectively

1. A.Toluidine, Phenolphthalein
2. B.Carbolic acid, Phenolphthalein
3. C.Salicylaldehyde, Phenolphthalein
4. D.Anisole, methyl orange