Consider the reactions
`(i) PCl_(5)(g) hArr PCl_(3)(g)+Cl_(2)(g)`
`(ii) N_(2)O_(4) (g) hArr 2NO_(2)(g)`
The addition of an inert gas at constant volume

Options

A. a. will increase the dissociation of `PCl_(5)` as well `N_(2) O_(4)`
B. b. will reduce the dissociation of `PCl_(5)` as well as `N_(2)O_(4)`
C. c. will increase the dissociation of `PCl_(5)` and step up the formation of `NO_(2)`
D. d. will not disturb the equilibrium of the reactions.

Explanation

To solve the question regarding the effect of adding an inert gas at constant volume on the given reactions, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Reactions**:
- The first reaction is:
\[ \text{PCl}_5(g) \rightleftharpoons \text{PCl}_3(g) + \text{Cl}_2(g) \]
- The second reaction is:
\[ \text{N}_2\text{O}_4(g) \rightleftharpoons 2\text{NO}_2(g) \]

2. **Identify the Effect of Inert Gas Addition**:
- When an inert gas is added to a system at constant volume, the total pressure of the system increases, but the partial pressures of the reactants and products do not change because the volume remains constant.

3. **Apply Le Chatelier's Principle**:
- Le Chatelier's principle states that if a system at equilibrium is subjected to a change in conditions, the system will adjust to counteract that change and restore a new equilibrium.
- In this case, since the concentration (or partial pressure) of the reactants and products does not change due to the addition of an inert gas, the equilibrium position will not shift.

4. **Conclusion**:
- Since the addition of an inert gas at constant volume does not change the concentration of the reactants or products, it will not disturb the equilibrium of either reaction.
- Therefore, the correct answer is that the equilibrium will not be disturbed.

### Final Answer:
The addition of an inert gas at constant volume will not disturb the equilibrium of the reactions.