Chemistry - Chemical Equilibrium Question with Solution | TestHub

(P) $H_{2}O(l)\rightleftharpoons H_{2}O(g)$: Adding pure liquid water does not change its active mass, so it does not shift the equilibrium (2), and the concentration of the product remains constant (4).

(Q) $I_3^{-}(aq)\rightleftharpoons I_2(aq)+I^{-}(aq)$: Adding water dilutes the solution, which increases the volume and favors the forward reaction (1) because it has more moles of aqueous particles. However, the overall concentration of the products decreases (3) due to dilution.

(R) $2AB(g)\rightleftharpoons A_2(g)+B_2(g)$: Since $\Delta n_g=0$, increasing the volume does not shift the equilibrium (2), but it expands the system, causing the concentration of products to decrease (3).

(S) $A_2(g)\rightleftharpoons 2A(g)$: Adding a catalyst only accelerates the rate of reactions without shifting the equilibrium position, meaning it does not shift the equilibrium state (2), and product concentration remains constant (4).

Conclusion: In option (A), Q-1,4 is an incorrect match because the concentration of the product decreases (3) instead of remaining constant (4).