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38
Subjective

Match the following equilibria with the corresponding condition.

A. Liquid $$\rightleftharpoons$$ Vapour 1. Saturated solution
B. Solid $$\rightleftharpoons$$ Liquid 2. Boiling point
C. Solid $$\rightleftharpoons$$ Vapour 3. Sublimation point
D. Solute (s) $$\rightleftharpoons$$ Solute (solution) 4. Melting point
5. Unsaturated solution

Explanation

A. $\rightarrow(2)$

B. $\rightarrow(4)$

C. $\rightarrow(3)$

D. $\rightarrow$ (1)

A. Liquid $\rightleftharpoons$ Vapour equilibrium exists at the boiling point.

B. Solid $\rightleftharpoons$ Liquid equilibrium exists at the melting point.

C. Solid $\rightleftharpoons$ Vapour equilibrium exists at the sublimation point.

D. Solute $(s) \rightleftharpoons$ Solute (solution) equilibrium exists at saturated solution.

39
Subjective

For the reaction, $\mathrm{N}_2(\mathrm{~g})+3 \mathrm{H}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{NH}_3(\mathrm{~g})$

Equilibrium constant, $\mathrm{K}_{\mathrm{c}}=\frac{\left[\mathrm{NH}_3\right]^2}{\left[\mathrm{~N}_2\right]\left[\mathrm{H}_2\right]^3}$

Some reactions are written below in Column I and their equilibrium constants in terms of $K_c$ are written in Column II. Match the following reactions with the corresponding equilibrium constant.

Column I
(Reaction)		 Column II
(Equilibrium constant)
A. $$
2 \mathrm{~N}_2(\mathrm{~g})+6 \mathrm{H}_2(\mathrm{~g}) \rightleftharpoons 4 \mathrm{NH}_3(\mathrm{~g})
$$		 1. $$
2 K_c
$$
B. $$
2 \mathrm{NH}_3(\mathrm{~g}) \rightleftharpoons 2 \mathrm{~N}_2(\mathrm{~g})+3 \mathrm{H}_2(\mathrm{~g})
$$		 2. $$
K_c^{1 / 2}
$$
C. $$
\frac{1}{2} \mathrm{~N}_2(\mathrm{~g})+\frac{3}{2} \mathrm{H}_2(\mathrm{~g}) \rightleftharpoons \mathrm{NH}_3(\mathrm{~g})
$$		 3. $$
\frac{1}{K_c}
$$
4. $$
K_c^2
$$

Explanation

$$\mathrm{A.\to(4)\quad B.\to(3)\quad C.\to(2)}$$

For the reaction,

$\mathrm{N}_2(\mathrm{~g})+3 \mathrm{H}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{NH}_3(\mathrm{~g})$

Equilibrium constant $K_{\mathrm{c}}=\frac{\left[\mathrm{NH}_3\right]^2}{\left[\mathrm{~N}_2\right]\left[\mathrm{H}_2\right]^3}$

A. The given reaction $\left[2 \mathrm{~N}_2(g)+6 \mathrm{H}_2(g) \rightleftharpoons 4 \mathrm{NH}_3(g)\right]$ is twice the above reaction. Hence, $K=K_c^2$

B. The reaction $\left[2 \mathrm{NH}_3(g) \rightleftharpoons \mathrm{N}_2(g)+3 \mathrm{H}_2(g)\right]$ is reverse of the above reaction. Hence, $K=\frac{1}{K_c}$

C. The reaction $\left[\frac{1}{2} \mathrm{~N}_2(g)+\frac{3}{2} \mathrm{H}_2(g) \rightleftharpoons \mathrm{NH}_3(g)\right]$ is half of the above reaction. Hence, $K=\sqrt{K_c}=K_c^{\frac{1}{2}}$.

40
Subjective

Match standard free energy of the reaction with the corresponding equilibrium constant.

A. $$
\Delta G^{\ominus}>0
$$
 1. $$K > 1$$
B. $$
\Delta G^{\ominus}<0
$$		 2. $$K=1$$
C. $$
\Delta G^{\ominus}=0
$$		 3. $$K=0$$
4. $$K < 1$$

Explanation

A. $\rightarrow(4)$

B. $\rightarrow$ (1)

C. $\rightarrow(2)$

As we know that, $\Delta G^{\ominus}=-R T \ln K$

A. If $\Delta G^{\circ}>0$, i.e., $\Delta G^{\circ}$ is positive, then $\ln K$ is negative i.e., $K<1$.

B. If $\Delta G^{\circ}<0$, i.e., $\Delta G^{\circ}$ is negative then $\ln K$ is positive i.e., $K>1$.

C. If $\Delta G^{\ominus}=0, \ln K=0$, i.e., $K=1$.

41
Subjective

Match the following species with the corresponding conjugate acid.

Species Conjugate acid
A. $$
\mathrm{NH}_3
$$
 1. $$
\mathrm{CO}_3^{2-}
$$
B. $$
\mathrm{HCO}_3^{-}
$$
 2. $$
\mathrm{NH}_4^{+}
$$
C. $$
\mathrm{H}_2 \mathrm{O}
$$
 3. $$
\mathrm{H}_3 \mathrm{O}^{+}
$$
D. $$
\mathrm{HSO}_4^{-}
$$		 4. $$
\mathrm{H}_2 \mathrm{SO}_4
$$
5. $$
\mathrm{H}_2 \mathrm{CO}_3
$$

Explanation

A. $\rightarrow$ (2)

B. $\rightarrow(5)$

C. $\rightarrow(3)$

D. $\rightarrow$ (4)

As conjugate acid $\rightarrow$ Base $+\mathrm{H}^{+}$

A. $\mathrm{NH}_3+\mathrm{H}^{+} \longrightarrow \mathrm{NH}_4^{+}$

B. $\mathrm{HCO}_3^{-}+\mathrm{H}^{+} \longrightarrow \mathrm{H}_2 \mathrm{CO}_3$

C. $\mathrm{H}_2 \mathrm{O}+\mathrm{H}^{+} \longrightarrow \mathrm{H}_3 \mathrm{O}^{+}$

D. $\mathrm{HSO}_4^{-}+\mathrm{H}^{+} \longrightarrow \mathrm{H}_2 \mathrm{SO}_4$

42
Subjective

Match the following graphical variation with their description.

A B
A. 1. Variation in product concentration with time
B. 2. Reaction at equilibrium
C. 3. Variation in reactant concentration with time

Explanation

A. $\rightarrow$ (3)

B. $\rightarrow(1)$

C. $\rightarrow(2)$

A. Graph (A) represents variation of reactant concentration with time.

B. Graph (B) represents variation of product concentration with time.

C. Graph (C) represents reaction at equilibrium.

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