Which one of the following conditions will favour maximum formation of the product in the reaction.
` A_2(g) +B_2(g) hArr X_2(g) , Delta rH =-XkJ ? `

Options

A. low temperature and high pressure
B. Low temperature and low pressure
C. High temperature and high pressure
D. High temperature and low pressure.

Answer

To determine the conditions that will favor the maximum formation of the product in the reaction \( A_2(g) + B_2(g) \rightleftharpoons X_2(g) \) with \( \Delta_rH = -X \, \text{kJ} \), we will analyze the effects of temperature and pressure based on Le Chatelier's principle.

### Step-by-Step Solution:

1. **Identify the Reaction Type**:
The reaction is given as:
\[ A_2(g) + B_2(g) \rightleftharpoons X_2(g) \]
The enthalpy change \( \Delta_rH \) is negative, indicating that the reaction is exothermic (it releases heat).

**Hint**: Remember that a negative \( \Delta H \) indicates an exothermic reaction.

2. **Analyze the Effect of Pressure**:
- Count the number of moles of gas on each side of the reaction:
- Reactants: \( A_2 + B_2 \) = 2 moles
- Products: \( X_2 \) = 1 mole
- According to Le Chatelier's principle, increasing the pressure will favor the side with fewer moles of gas. Since the product side has fewer moles (1 mole) compared to the reactant side (2 moles), increasing the pressure will favor the formation of \( X_2 \).

**Hint**: Increasing pressure shifts the equilibrium toward the side with fewer gas moles.

3. **Analyze the Effect of Temperature**:
- For exothermic reactions, lowering the temperature favors the formation of products. Since our reaction is exothermic, a low temperature will favor the forward reaction (formation of \( X_2 \)).
- Conversely, increasing the temperature would favor the reverse reaction (formation of reactants).

**Hint**: For exothermic reactions, lower temperatures favor product formation.

4. **Combine the Findings**:
- From the analysis, we conclude that to maximize the formation of the product \( X_2 \):
- **High Pressure** is needed to favor the side with fewer moles.
- **Low Temperature** is needed to favor the exothermic reaction.

5. **Select the Correct Option**:
- The conditions that favor maximum formation of the product are **high pressure and low temperature**.

### Final Answer:
The conditions that will favor maximum formation of the product \( X_2 \) are **high pressure and low temperature**.