Factors affecting equilibrium; Le Chatelier's principle — NEET & JEE Questions

Question 1 · difficulty L1 · recall

Le Chatelier's principle predicts that when an equilibrium system is disturbed, it shifts so as to

• A. oppose the imposed change
• B. amplify the imposed change
• C. stop all reactions
• D. make forward and reverse rates unequal forever

Question 2 · difficulty L2 · understanding

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.

Question 3 · difficulty L2 · understanding

Consider the following equation: $2 \mathrm{SO}_{2}(g)+\mathrm{O}_{2}(g) \rightleftharpoons 2 \mathrm{SO}_{3}(g), \Delta H=-190 \mathrm{~kJ}$ The number of factors which will increase the yield of $\mathrm{SO}_{3}$ at equilibrium from the following is _______. A. Increasing temperature B. Increasing pressure C. Adding more $\mathrm{SO}_{2}$ D. Adding more $\mathrm{O}_{2}$ E. Addition of catalyst

Question 4 · difficulty L2 · understanding

Consider the reaction, A $$\rightleftharpoons$$ B at 1000 K. At time t', the temperature of the system was increased to 2000 K and the system was allowed to reach equilibrium. Throughout this experiment the partial pressure of A was maintained at 1 bar. Given, below is the plot of the partial pressure of B with time. What is the ratio of the standard Gibbs energy of the reaction at 1000 K to that at 2000 K?

Question 5 · difficulty L2 · understanding

The following reaction occurs in the Blast furnance where iron ore is reduced to iron metal $$\mathrm{Fe}_2 \mathrm{O}_{3(s)}+3 \mathrm{CO}_{(g)} \rightleftharpoons \mathrm{Fe}_{(\mathrm{l})}+3 \mathrm{CO}_{2(g)}$$ Using the Le-chatelier's principle, predict which one of the following will not disturb the equilibrium.

• A. Addition of $$\mathrm{CO}_2$$
• B. Removal of $$\mathrm{CO}$$
• C. Addition of $$\mathrm{Fe}_2 \mathrm{O}_3$$
• D. Removal of $$\mathrm{CO}_2$$

Question 6 · difficulty L2 · understanding

Higher yield of NO in $\mathrm{N}_2(\mathrm{~g})+\mathrm{O}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{NO}(\mathrm{g})$ can be obtained at $\left[\Delta \mathrm{H}\right.$ of the reaction $\left.=+180.7 \mathrm{~kJ} \mathrm{~mol}^{-1}\right]$ A. Higher temperature B. Lower temperature C. Higher concentration of $\mathrm{N}_2$ D. Higher concentration of $\mathrm{O}_2$ Choose the correct answer from the options given below :

• A. B, C, D only
• B. A, C, D only
• C. A, D only
• D. B, C only

Question 7 · difficulty L3 · understanding

At 298 K $$\mathrm{N_2~(g)+3H_2~(g)\rightleftharpoons~2NH_3~(g),~K_1=4\times10^5}$$ $$\mathrm{N_2~(g)+O_2~(g)\rightleftharpoons~2NO~(g),~K_2=1.6\times10^{12}}$$ $$\mathrm{H_2~(g)+\frac{1}{2}O_2~(g)\rightleftharpoons~H_2O~(g),~K_3=1.0\times10^{-13}}$$ Based on above equilibria, then equilibrium constant of the reaction, $$\mathrm{2NH_3(g)+\frac{5}{2}O_2~(g)\rightleftharpoons~2NO~(g)+3H_2O~(g)}$$ is ____________ $$\times10^{-33}$$ (Nearest integer).

Question 8 · difficulty L3 · understanding

40% of HI undergoes decomposition to H 2 and I 2 at 300 K. $$\Delta$$G$$^\Theta$$ for this decomposition reaction at one atmosphere pressure is __________ J mol $$-$$1 . [nearest integer] (Use R = 8.31 J K $$-$$1 mol $$-$$1 ; log 2 = 0.3010, ln 10 = 2.3, log 3 = 0.477)

Question 9 · difficulty L3 · understanding

Consider the following gaseous equilibrium in a closed container of volume ' $V$ ' at $\mathrm{T}(\mathrm{K})$. $$\mathrm{P}_2(\mathrm{~g})+\mathrm{Q}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{PQ}(\mathrm{~g})$$ 2 moles each of $\mathrm{P}_2(\mathrm{~g}), \mathrm{Q}_2(\mathrm{~g})$ and $\mathrm{PQ}(\mathrm{g})$ are present at equilibrium. Now one mole each of ' $\mathrm{P}_2$ ' and ' $\mathrm{Q}_2$ ' are added to the equilibrium keeping the temperature at $\mathrm{T}(\mathrm{K})$. The number of moles of $\mathrm{P}_2, \mathrm{Q}_2$ and PQ at the new equilibrium, respectively, are

• A. $2.56,1.62,2.24$
• B. $2.67,2.67,2.67$
• C. 1.21, 2.24, 1.56
• D. $1.66,1.66,1.66$

Question 10 · difficulty L3 · understanding

In the following system, $\mathrm{PCl}_5(\mathrm{~g}) \leftrightharpoons \mathrm{PCl}_3(\mathrm{~g})+\mathrm{Cl}_2(\mathrm{~g})$ at equilibrium, upon addition of xenon gas at constant T \& p , the concentration of

• A. $\mathrm{PCl}_5, \mathrm{PCl}_3 \& \mathrm{Cl}_2$ remain constant
• B. $\mathrm{PCl}_3$ will increase
• C. $\mathrm{Cl}_2$ will decrease
• D. $\mathrm{PCl}_5$ will increase