Question

Which of the following is not a general characteristic of equilibria involving physical processes?

• A. All the physical processes stop at equilibrium.
• B. The opposing processes occur at the same rate and there is dynamic but stable condition.
• C. Equilibrium is possible only in a closed system at a given temperature.
• D. All measurable properties of the system remain constant.

Answer 1

The correct option is A All the physical processes stop at equilibrium.

A. Equilibrium is possible only in a closed system at a given temperature. A reversible reaction becomes irreversible in open system and do not attain equilibrium.

B. It is correct statement because after attaining equilibrium, changes takes place in both directions but at the same rate. So, all measurable properties of the system remain constant.

C. All the physical processes stop at equilibrium.

It is incorrect statement because the equilibrium involving physical processes are dynamic in nature. The reaction proceeds in both directions. But since their rate is the same, it seems that the transformation has stopped but the changes remain constant because at equilibrium, both the reactant and products form at the same rate.

D. The opposing processes occur at the same rate and there is dynamic but stable condition.

It is correct because at equilibrium both the formation of products and conversion of products to reactants occur at the same rate and therefore changes reflecting the process i.e., concentration/pressure remains constant.

Therefore, option $\left(C\right)$ is the answer because as per the given question, it is an incorrect statement for equilibria involving physical processes.