The gaseous reaction `A_((g)) + B_((g)) hArr 2C_((g)) + D_((g)) + q ` kJ is most favoured at :

Options

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

Answer

To determine the conditions that favor the reaction \( A_{(g)} + B_{(g)} \rightleftharpoons 2C_{(g)} + D_{(g)} + q \) kJ, we need to analyze the characteristics of the reaction based on Le Chatelier's principle and the nature of the reaction.

### Step 1: Identify the nature of the reaction
The reaction is given as:
\[ A_{(g)} + B_{(g)} \rightleftharpoons 2C_{(g)} + D_{(g)} + q \]

This indicates that the reaction involves gaseous reactants and products.

### Step 2: Determine if the reaction is exothermic or endothermic
The reaction is described as exothermic because it releases \( q \) kJ of energy. In an exothermic reaction, heat can be considered as a product.

### Step 3: Analyze the effect of temperature
For exothermic reactions, according to Le Chatelier's principle, lowering the temperature shifts the equilibrium to the right (toward the products) to produce more heat. Therefore, low temperatures favor the formation of products in exothermic reactions.

### Step 4: Analyze the effect of pressure
Next, we look at the number of moles of gases on both sides of the reaction:
- Reactants: 1 mole of \( A \) + 1 mole of \( B \) = 2 moles
- Products: 2 moles of \( C \) + 1 mole of \( D \) = 3 moles

Since there is an increase in the number of moles of gas when moving from reactants to products (from 2 moles to 3 moles), according to Le Chatelier's principle, decreasing the pressure will favor the side with more moles of gas. Therefore, low pressure will also favor the formation of products.

### Step 5: Conclusion
The reaction \( A_{(g)} + B_{(g)} \rightleftharpoons 2C_{(g)} + D_{(g)} + q \) is most favored at low temperature and low pressure.

### Final Answer
The conditions that favor the reaction are:
- Low temperature
- Low pressure