As per Le-chatelier's principle any equilibrium state nullifies the effect of a change imposed on it to establish new equilibrium state.
`N_(2) O_(4) (g) hArr 2NO_(2) (g), Delta` H = +ve
Decomposition of `N_(2)O_(4)` can be encouraged by._____

Answer

To solve the question regarding the decomposition of \( N_2O_4 \) and how to encourage this reaction according to Le Chatelier's principle, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reaction**: The given equilibrium reaction is:
\[ N_2O_4 (g) \rightleftharpoons 2 NO_2 (g) \]
with \( \Delta H = +ve \), indicating that the reaction is endothermic (absorbs heat).

2. **Understand Le Chatelier's Principle**: According to Le Chatelier's principle, if a change (stress) is applied to a system at equilibrium, the system will adjust to counteract that change and establish a new equilibrium.

3. **Analyze the Effects of Changes**:
- **Change in Concentration**:
- To encourage the forward reaction (decomposition of \( N_2O_4 \)), we can increase the concentration of \( N_2O_4 \). This will shift the equilibrium to the right to consume the added reactant.

- **Change in Temperature**:
- Since the reaction is endothermic, increasing the temperature will favor the forward reaction. The system will absorb the added heat, promoting the formation of \( NO_2 \).

- **Change in Pressure**:
- In the forward reaction, the number of moles of gas increases (from 1 mole of \( N_2O_4 \) to 2 moles of \( NO_2 \)). According to Le Chatelier's principle, decreasing the pressure will favor the side with more moles of gas, which in this case is the right side (products).

4. **Conclusion**:
- To encourage the decomposition of \( N_2O_4 \), the following conditions should be applied:
- Increase the concentration of \( N_2O_4 \).
- Increase the temperature.
- Decrease the pressure.

### Final Answer:
The decomposition of \( N_2O_4 \) can be encouraged by increasing the concentration of \( N_2O_4 \), increasing the temperature, and decreasing the pressure.

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