For the Chemical reaction `A_(2(g)) + B_(2(g)) hArr 2 AB(g)` the amount of AB at equilibrium is affected by

Options

A. Temperature and pressure
B. Temperature only
C. Pressure only
D. Temperature, pressure and catalyst

Answer

To determine how the amount of AB at equilibrium is affected in the reaction \( A_2(g) + B_2(g) \rightleftharpoons 2AB(g) \), we can analyze the factors that influence chemical equilibrium.

### Step-by-Step Solution:

1. **Identify the Reaction**:
The given reaction is:
\[ A_2(g) + B_2(g) \rightleftharpoons 2AB(g) \]
This is a gaseous reaction involving two reactants and one product.

2. **Understand the Concept of Equilibrium**:
At equilibrium, the rate of the forward reaction equals the rate of the reverse reaction. The concentrations of reactants and products remain constant.

3. **Factors Affecting Equilibrium**:
The amount of product (AB) at equilibrium can be affected by:
- **Temperature**: Changes in temperature can shift the equilibrium position depending on whether the reaction is exothermic or endothermic.
- **Pressure**: For gaseous reactions, changes in pressure can affect the equilibrium position, particularly if there is a difference in the number of moles of gas on each side of the reaction.
- **Catalysts**: Catalysts speed up the rate of both the forward and reverse reactions equally but do not affect the position of equilibrium.

4. **Analyze the Reaction**:
- In this reaction, we have 1 mole of \( A_2 \) and 1 mole of \( B_2 \) on the reactants side (total of 2 moles) and 2 moles of \( AB \) on the products side (total of 2 moles).
- Since the number of moles of gas is the same on both sides (2 moles of reactants and 2 moles of products), changes in pressure will not have an effect on the equilibrium position.

5. **Determine the Effect of Temperature**:
- If the forward reaction is exothermic, increasing the temperature will favor the reverse reaction, thus decreasing the amount of AB.
- Conversely, if the forward reaction is endothermic, increasing the temperature will favor the formation of AB, thus increasing its amount.
- Therefore, temperature has a significant effect on the amount of AB at equilibrium.

6. **Conclusion**:
Based on the analysis, the amount of AB at equilibrium is affected by temperature only, and pressure does not have an effect due to the equal number of moles of gas on both sides of the reaction.

### Final Answer:
The amount of AB at equilibrium is affected by **temperature only**.