121. When hydrochloric acid is added to cobalt nitrate solution at room temperature, the following reaction takes place and the reaction mixture becomes blue. On cooling the mixture, it becomes pink. On the basis of this information mark the correct answer. $$\mathop {\left[ {Co{{\left( {{H_2}O} \right)}_6}} \right]_{\left( {aq} \right)}^{3 + }}\limits_{{\text{Pink}}} + 4Cl_{\left( {aq} \right)}^ - \rightleftharpoons $$     $$\mathop {\left[ {CoC{l_4}} \right]_{\left( {aq} \right)}^{2 - }}\limits_{{\text{Blue}}} + 6{H_2}{O_{\left( l \right)}}$$

A $$\Delta H > 0$$  for the reaction
B $$\Delta H < 0$$  for the reaction
C $$\Delta H = 0$$  for the reaction
D The sign of $$\Delta H$$  cannot be predicted on the basis of this information.
Answer :   $$\Delta H > 0$$  for the reaction
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122. The solubility in water of a sparingly soluble salt $$A{B_2}$$  is $$1.0 \times {10^{ - 5}}mol\,{L^{ - 1}}.$$    Its solubility product number will be

A 4 × 10-10
B 1 × 10-15
C 1 × 10-10
D 4 × 10-15
Answer :   4 × 10-15
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123. The equilibrium constant for the reaction
$$\eqalign{ & S{O_3}\left( g \right) \rightleftharpoons S{O_2}\left( g \right) + \frac{1}{2}{O_2}\left( g \right) \cr & {\text{is}}\,{K_c} = 4.9 \times {10^{ - 2}}.\,{\text{The value of }}{{\text{K}}_c}{\text{ for the reaction}} \cr & {\text{2S}}{{\text{O}}_2}\left( g \right) + {O_2}\left( g \right) \rightleftharpoons 2S{O_3}\left( g \right) \cr & {\text{will}}\,{\text{be}} \cr} $$

A $${\text{9}}{\text{.8}} \times {\text{1}}{{\text{0}}^{ - 2}}$$
B $$4.9 \times {10^{ - 2}}$$
C 416
D $$2.40 \times {10^{ - 3}}$$
Answer :   416
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124. Study the figure given below and mark the correct statement about $${K_c}$$  and dependence of extent of reaction on it.
Chemical Equilibrium mcq question image
$$X$$
$$Y$$
$$Z$$
(a) Reaction does not occur Reaction proceeds to completion Reaction does not occur
(b) Reaction completes Reaction does not occur Reactants and products are at equilibrium
(c) Reaction hardly occurs Reactants and products are at equilibrium Reaction proceeds to completion
(d) Reaction proceeds to completion Reactants and products are at equilibrium Reaction hardly occurs

A (a)
B (b)
C (c)
D (d)
Answer :   (c)
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125. According to Le-Chatelier’s principle, adding heat to a solid $$ \rightleftharpoons $$ liquid equilibrium will cause the

A temperature to increase
B temperature to decrease
C amount of liquid to decrease
D amount of solid to decrease
Answer :   amount of solid to decrease
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126. When two reactants, $$A$$ & $$B$$ are mixed to give products $$C$$ & $$D,$$ the reaction quotient $$Q,$$ at the initial stages of the reaction

A is zero
B decreases with time
C is independent of time
D increases with time
Answer :   increases with time
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127. At constant temperature, the equilibrium constant $$\left( {{K_p}} \right)$$  for the decomposition reaction $${N_2}{O_4} \rightleftharpoons 2N{O_2}$$    is expressed by $${K_p} = \frac{{\left( {4{x^2}P} \right)}}{{\left( {1 - {x^2}} \right)}},$$    where $$P$$ = pressure, $$x$$ = extent of decomposition. Which one of the following statements is true?

A $${{K_p}}$$  increases with increase of $$P$$
B $${{K_p}}$$  increases with increase of $$x$$
C $${{K_p}}$$  increases with decrease of $$x$$
D $${{K_p}}$$  remains constant with change in $$P$$ and $$x$$
Answer :   $${{K_p}}$$  remains constant with change in $$P$$ and $$x$$
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128. The equilibrium constant for the reaction $$W + X \rightleftharpoons Y + Z$$     is 9. If one mole of each of $$w$$ and $$x$$ are mixed and there is no change in volume, the number of moles of $$y$$ formed is

A 0.10
B 0.50
C 0.75
D 0.54
Answer :   0.75
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129. The Haber’s process for the formation of $$N{H_3}$$  at $$298K$$  is $${N_2} + 3{H_2} \rightleftharpoons 2N{H_3}\,;\Delta H = - 46.0\,kJ;$$        Which of the following is the correct statement

A The condition for equilibrium is $${G_{{N_2}}} + 3{G_{{H_2}}} = 2{G_{N{H_3}}}.$$     where $$G$$ is Gibb's free energy per mole of the gaseous species measured at that partial pressure.
B On adding $${N_2}$$ , the equilibrium will shift to forward direction because according to IInd law of thermodynamics the entropy must increase in the direction of spontaneous reaction
C The catalyst will increase the rate of forward reaction by 2 times and that of backward reaction by 1.5 times
D None of these
Answer :   The condition for equilibrium is $${G_{{N_2}}} + 3{G_{{H_2}}} = 2{G_{N{H_3}}}.$$     where $$G$$ is Gibb's free energy per mole of the gaseous species measured at that partial pressure.
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130. For a reversible reaction at $$298\,K$$  the equilibrium constant $$K$$  is 200. What is the value of $$\Delta {G^ \circ }$$  at $$298\,K?$$

A $$ - 13.13\,kcal$$
B $$ - 0.13\,kcal$$
C $$ - 3.158\,kcal$$
D $$ - 0.413\,kcal$$
Answer :   $$ - 3.158\,kcal$$
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