The yield of product in the reaction `2A_((g)) + B_((g)) hArr 2C_((g)) + `Q K J would be lower at :

Options

A. low temperature and low pressure
B. high temperature and high pressure
C. low temperature and too high pressure
D. high temperature and low pressure

Answer

To determine the conditions under which the yield of the product in the reaction \(2A_{(g)} + B_{(g)} \rightleftharpoons 2C_{(g)} + Q \, kJ\) would be lower, we need to analyze the factors affecting the equilibrium of this reaction.

### Step-by-Step Solution:

1. **Identify the Reaction Type**:
The reaction given is:
\[ 2A_{(g)} + B_{(g)} \rightleftharpoons 2C_{(g)} + Q \, kJ \]
This indicates that the reaction is exothermic in the forward direction because heat (Q) is released.

**Hint**: Recognize whether the reaction is exothermic or endothermic based on the heat term.

2. **Understand Le Chatelier's Principle**:
According to Le Chatelier's principle, if a system at equilibrium is subjected to a change in concentration, temperature, or pressure, the system will adjust to counteract that change and restore a new equilibrium.

**Hint**: Remember that increasing temperature favors the endothermic direction and decreasing pressure favors the side with more moles of gas.

3. **Analyze Temperature Effects**:
Since the forward reaction is exothermic, increasing the temperature will favor the reverse reaction (endothermic). Therefore, a higher temperature will result in a lower yield of products (C).

**Hint**: Consider how temperature changes affect the direction of the reaction based on whether it is exothermic or endothermic.

4. **Analyze Pressure Effects**:
In the given reaction, we have:
- Reactants: \(2A + B\) (total 3 moles)
- Products: \(2C\) (total 2 moles)

When the pressure is decreased, the equilibrium will shift towards the side with more moles of gas to counteract the change. Thus, lower pressure will favor the reverse reaction, resulting in a lower yield of products.

**Hint**: Count the number of moles on each side of the reaction to determine how pressure changes will affect equilibrium.

5. **Conclusion**:
The yield of the product will be lower under the following conditions:
- **High Temperature**: Favors the reverse reaction.
- **Low Pressure**: Favors the reverse reaction due to more moles of gas.

Therefore, the conditions that lead to a lower yield of products \(C\) are high temperature and low pressure.

**Final Answer**: The yield of product will be lower at high temperature and low pressure.