Chemical & Ionic Equilibrium · JEE Main previous year questions

The solubility product of $\mathrm{Cr}(\mathrm{OH}{)}_3$ at 298 K is $6.0\times 10^{-31}$. The concentration of hydroxide ions in a saturated solution of $\mathrm{Cr}(\mathrm{OH}{)}_3$ will be :

1. A.$(2.22\times 10^{-31}{)}^{1/4}$
2. B.$(4.86\times 10^{-29}{)}^{1/4}$
3. C.$(18\times 10^{-31}{)}^{1/4}$
4. D.$(18\times 10^{-31}{)}^{1/2}$

The strength of an aqueous $\mathrm{NaOH}$ solution is most accurately determined by titrating : (Note : consider that an appropriate indicator is used)

1. A.Aq. $\mathrm{NaOH}$ in a pipette and aqueous oxalic acid in a burette
2. B.Aq. $\mathrm{NaOH}$ in a burette and aqueous oxalic acid in a conical flask
3. C.Aq. $\mathrm{NaOH}$ in a volumetric flask and concentrated ${\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$ in a conical flask
4. D.Aq. $\mathrm{NaOH}$ in a burette and concentrated ${\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$ in a conical flask

For an electrochemical cell $$\mathrm{Sn}(\mathrm{s})\mid \mathrm{S}{\mathrm{n}}^{2+}(\mathrm{aq},1M)\parallel \mathrm{P}{\mathrm{b}}^{2+}(\mathrm{aq},1M)\mid \mathrm{Pb}(\mathrm{s})$$ the ratio $\frac{[{\mathrm{Sn}}^{2+}]}{[{\mathrm{Pb}}^{2+}]}$ when this cell attains equilibrium is _______. (Given $E_{\mathrm{S}{\mathrm{n}}^{2+}|Sn}^0=-0.14\mathrm{V}$, $E_{\mathrm{P}{\mathrm{b}}^{2+}|Pb}^0=-0.13\mathrm{V}$, $\frac{2.303RT}{F}=0.06$)

Two solutions, A and B, each of 100L was made by dissolving 4g of $\mathrm{NaOH}$ and 9.8 g of ${\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$ in water, respectively. The pH of the resultant solution obtained from mixing 40L of solution A and 10L of solution B is :

For the reaction : $$\mathrm{A}(l)\to 2\mathrm{B}(g)$$ $\Delta U=2.1\text{ kcal}$, $\Delta S=20\text{ cal }{K}^{-1}$ at $300\text{ K}$ Hence $\Delta G$ in kcal is :

3 g of acetic acid is added to 250 mL of 0.1 M HCl and the solution made up to 500 mL. To 20 mL of this solution $\frac{1}{2}\text{ mL}$ of 5 M NaOH is added. The pH of the solution is _______. [Given : pKa of acetic acid = 4.75, molar mass of acetic acid = 60 g/mol, $\log 3=0.4771$] Neglect any changes in volume.

What is the molar solubility of ${\text{Al(OH)}}_3$ in 0.2 M NaOH solution ? Given that, solubility product of ${\text{Al(OH)}}_3=2.4\times 10^{-24}$ :

1. A.$3\times 10^{-22}$
2. B.$3\times 10^{-19}$
3. C.$12\times 10^{-21}$
4. D.$12\times 10^{-22}$

The molar solubility of ${\text{Cd(OH)}}_2$ is $1.84\times 10^{-5}\text{ M}$ in water. The expected solubility of ${\text{Cd(OH)}}_2$ in a buffer solution of pH = 12 is :

1. A.$2.49\times 10^{-10}\text{ M}$
2. B.$1.84\times 10^{-9}\text{ M}$
3. C.$6.23\times 10^{-11}\text{ M}$
4. D.$\frac{2.49}{1.84}\times 10^{-9}M$

In which one of the following equilibria, ${\text{K}}_{\text{p}}\ne {\text{K}}_{\text{C}}$ ?

1. A.$2\text{NO(g)}\rightleftharpoons {\text{N}}_2\text{(g)}+{\text{O}}_2\text{(g)}$
2. B.$2\text{C(s)}+{\text{O}}_2\text{(g)}\rightleftharpoons 2\text{CO(g)}$
3. C.$2\text{HI(g)}\rightleftharpoons {\text{H}}_2\text{(g)}+{\text{I}}_2\text{(g)}$
4. D.${\text{NO}}_2\text{(g)}+{\text{SO}}_2\text{(g)}\rightleftharpoons \text{NO(g)}+{\text{SO}}_3\text{(g)}$

Consider the following statements (a) The pH of a mixture containing 400 mL of 0.1 M ${\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$ and 400 mL of 0.1 M NaOH will be approximately 1.3 (b) Ionic product of water is temperature dependent. (c) A monobasic acid with Ka = $10^{-5}$ has pH = 5. The degree of dissociation of this acid is 50 %. (d) The Le Chatelier's principle is not applicable to common-ion effect. The correct statements are :

1. A.(a) and (b)
2. B.(a), (b) and (c)
3. C.(a), (b) and (d)
4. D.(b) and (c)

For the reaction, $2S{\mathrm{O}}_2(\mathrm{g})+{\mathrm{O}}_2(\mathrm{g})=2S{\mathrm{O}}_3(\mathrm{g})$, $\Delta \mathrm{H}=-57.2\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$ and ${\mathrm{K}}_{\mathrm{C}}=1.7\times 10^{16}$ Which of the following statement is incorrect ?

1. A.The equilibrium will shift in forward direction as the pressure increase.
2. B.The addition of inert gas at constant volume will not affect the equilibrium constant.
3. C.The equilibrium constant is large suggestive of reaction going to completion and so no catalyst is required.
4. D.The equilibrium constant decreases as the temperature increase.

The pH of a 0.02 M $\mathrm{N}{\mathrm{H}}_4\mathrm{Cl}$ solution will be : [given ${\mathrm{K}}_{\mathrm{b}}(\mathrm{N}{\mathrm{H}}_4\mathrm{OH})=10^{-5}$ and $\log 2=0.301$]

1. A.2.56
2. B.5.35
3. C.4.35
4. D.4.65

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

For the following reactions, equilibrium constants are given : $\mathrm{S}(\mathrm{s})+{\mathrm{O}}_2(\mathrm{g})\rightleftharpoons \mathrm{S}{\mathrm{O}}_2(\mathrm{g})$; $K_1=10^{52}$ $2S(\mathrm{s})+3{\mathrm{O}}_2(\mathrm{g})\rightleftharpoons 2S{\mathrm{O}}_3(\mathrm{g})$; $K_2=10^{129}$ The equilibrium constant for the reaction, $2S{\mathrm{O}}_2(\mathrm{g})+{\mathrm{O}}_2(\mathrm{g})\rightleftharpoons 2S{\mathrm{O}}_3(\mathrm{g})$ is :

1. A.$10^{181}$
2. B.$10^{25}$
3. C.$10^{77}$
4. D.$10^{154}$

The correct order for acid strength of compounds : $\mathrm{CH}\equiv \mathrm{CH},\mathrm{C}{\mathrm{H}}_3-\mathrm{C}\equiv \mathrm{CH}$ and $\mathrm{C}{\mathrm{H}}_2=\mathrm{C}{\mathrm{H}}_2$ is as follows

1. A.$\mathrm{CH}\equiv \mathrm{CH}>\mathrm{C}{\mathrm{H}}_2=\mathrm{C}{\mathrm{H}}_2>\mathrm{C}{\mathrm{H}}_3-\mathrm{C}\equiv \mathrm{CH}$
2. B.$\mathrm{C}{\mathrm{H}}_3-\mathrm{C}\equiv \mathrm{CH}>\mathrm{C}{\mathrm{H}}_2=\mathrm{C}{\mathrm{H}}_2>\mathrm{HC}\equiv \mathrm{CH}$
3. C.$\mathrm{HC}\equiv \mathrm{CH}>\mathrm{C}{\mathrm{H}}_3-\mathrm{C}\equiv \mathrm{CH}>\mathrm{C}{\mathrm{H}}_2=\mathrm{C}{\mathrm{H}}_2$
4. D.$\mathrm{C}{\mathrm{H}}_3-\mathrm{CH}\equiv \mathrm{CH}>\mathrm{CH}\equiv \mathrm{CH}>\mathrm{C}{\mathrm{H}}_2=\mathrm{C}{\mathrm{H}}_2$

1. A.$\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{COC}{\mathrm{H}}_3+\mathrm{PhMgX}$
2. B.$\mathrm{PhCOC}{\mathrm{H}}_3+\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{MgX}$
3. C.$\mathrm{PhCOC}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_3+\mathrm{C}{\mathrm{H}}_3\mathrm{MgX}$
4. D.$\mathrm{HCHO}+\mathrm{PhCH}(\mathrm{C}{\mathrm{H}}_3)\mathrm{C}{\mathrm{H}}_2\mathrm{MgX}$

In a chemical reaction, $\mathrm{A}+2B\stackrel{\mathrm{K}}{\rightleftharpoons }2C+\mathrm{D}$ the initial concentration of B was 1.5 times of the concentration of A, but the equilibrium concentrations of A and B were found to be equal. The equilibrium constant (K) for the aforesaid chemical reaction is -

1. A.16
2. B.1
3. C.1/4
4. D.4

Two solids dissociate as follows – $\mathrm{A}(\mathrm{s})\rightleftharpoons \mathrm{B}(\mathrm{g})+\mathrm{C}(\mathrm{g});{\mathrm{K}}_{p1}=\mathrm{x}\mathrm{at}{\mathrm{m}}^2$ $\mathrm{D}(\mathrm{s})\rightleftharpoons \mathrm{C}(\mathrm{g})+\mathrm{E}(\mathrm{g});{\mathrm{K}}_{p2}=\mathrm{y}\mathrm{at}{\mathrm{m}}^2$ The total pressure when both the solids dissociated simultaneously is -

1. A.$(x+y)\mathrm{atm}$
2. B.$(\sqrt{x+y})\mathrm{atm}$
3. C.$2(\sqrt{x+y})\mathrm{atm}$
4. D.$x^2+y^2\mathrm{atm}$

A metal on combustion in excess air forms X. X upon hydrolysis with water yields ${\mathrm{H}}_2{\mathrm{O}}_2$ and ${\mathrm{O}}_2$ along with another product. The metal is :

1. A.$\mathrm{Rb}$
2. B.$\mathrm{Mg}$
3. C.$\mathrm{Na}$
4. D.$\mathrm{Li}$

If $K_{sp}$ of $\mathrm{A}{\mathrm{g}}_2\mathrm{C}{\mathrm{O}}_3$ is $8\times 10^{-12}$, the molar solubility of $\mathrm{A}{\mathrm{g}}_2\mathrm{C}{\mathrm{O}}_3$ in 0.1 M $\mathrm{AgN}{\mathrm{O}}_3$ is -

1. A.$8\times 10^{-12}\mathrm{M}$
2. B.$8\times 10^{-10}\mathrm{M}$
3. C.$8\times 10^{-13}\mathrm{M}$
4. D.$8\times 10^{-11}\mathrm{M}$

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

For the equilibrium, $$2{\mathrm{H}}_2\mathrm{O}\rightleftharpoons {\mathrm{H}}_3{\mathrm{O}}^{+}+\mathrm{O}{\mathrm{H}}^{-},\text{ the value of }\Delta {\mathrm{G}}^{\circ }\text{ at }298\text{ K is approximately :}$$

1. A.$-80{\text{ kJ mol}}^{-1}$
2. B.$100{\text{ kJ mol}}^{-1}$
3. C.$-100{\text{ kJ mol}}^{-1}$
4. D.$80{\text{ kJ mol}}^{-1}$

Given the equilibrium constant: ${\mathrm{K}}_{\mathrm{C}}$ of the reaction : $$\mathrm{Cu}(\mathrm{s})+2A{\mathrm{g}}^{+}(\mathrm{aq})\to \mathrm{C}{\mathrm{u}}^{2+}(\mathrm{aq})+2Ag(\mathrm{s})$$ is $10\times 10^{15}$, calculate the ${\mathrm{E}}_{cell}^0$ of this reaction at $298\text{ K}$ $[2.303\frac{RT}{F}\text{ at }298\text{ K}=0.059\text{V}]$

1. A.$0.4736\text{ mV}$
2. B.$0.04736\text{ V}$
3. C.$0.4736\text{ V}$
4. D.$0.04736\text{ mV}$

The correct decreasing order for acid strength is :

1. A.$\mathrm{N}{\mathrm{O}}_2\mathrm{C}{\mathrm{H}}_2\mathrm{COOH}>\mathrm{FC}{\mathrm{H}}_2\mathrm{COOH}>\mathrm{CNC}{\mathrm{H}}_2\mathrm{COOH}>\mathrm{ClC}{\mathrm{H}}_2\mathrm{COOH}$
2. B.$\mathrm{FC}{\mathrm{H}}_2\mathrm{COOH}>\mathrm{NCC}{\mathrm{H}}_2\mathrm{COOH}>\mathrm{N}{\mathrm{O}}_2\mathrm{C}{\mathrm{H}}_2\mathrm{COOH}>\mathrm{ClC}{\mathrm{H}}_2\mathrm{COOH}$
3. C.$\mathrm{CNC}{\mathrm{H}}_2\mathrm{COOH}>{\mathrm{O}}_2\mathrm{NC}{\mathrm{H}}_2\mathrm{COOH}>\mathrm{FC}{\mathrm{H}}_2\mathrm{COOH}>\mathrm{ClC}{\mathrm{H}}_2\mathrm{COOH}$
4. D.$\mathrm{N}{\mathrm{O}}_2\mathrm{C}{\mathrm{H}}_2\mathrm{COOH}>\mathrm{NCC}{\mathrm{H}}_2\mathrm{COOH}>\mathrm{FC}{\mathrm{H}}_2\mathrm{COOH}>\mathrm{ClC}{\mathrm{H}}_2\mathrm{COOH}$

$20\text{ mL}$ of $0.1\text{ M }{\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$ solution is added to $30\text{ mL}$ of $0.2\text{ M }\mathrm{N}{\mathrm{H}}_4\mathrm{OH}$ solution. The pH of the resultant mixture is : $[\mathrm{p}{\mathrm{K}}_{\mathrm{b}}\text{ of }\mathrm{N}{\mathrm{H}}_4\mathrm{OH}=4.7]$.

1. A.5.2
2. B.9.0
3. C.5.0
4. D.9.4