The synthesis of ammonia is given as:
`N_(2)(g)+3H_(2)(g) hArr 2NH_(3)(g), DeltaH^(ɵ)=-92.6 kJ mol^(-1)` given `K_(c)=1.2` and temperature `(T)=375^(@)C`
Which of the following factors does not alter the yield of `NH_(3)` at equilibrium?

Options

A. Catalyst
B. Increase in pressure
C. Increase in temperature
D. Decrease in pressure

Explanation

To solve the problem regarding the synthesis of ammonia and the factors that do not alter the yield of NH3 at equilibrium, we can follow these steps:

### Step 1: Understand the Reaction
The synthesis of ammonia is represented by the equation:
\[ N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g) \]
This reaction is exothermic, as indicated by the negative enthalpy change (\( \Delta H^{\circ} = -92.6 \, \text{kJ mol}^{-1} \)).

### Step 2: Identify Factors Affecting Equilibrium
According to Le Chatelier's principle, the yield of products at equilibrium can be affected by:
1. **Temperature**: Changing the temperature can shift the equilibrium position.
2. **Pressure**: Increasing or decreasing pressure can also shift the equilibrium, especially in reactions involving gases.
3. **Concentration**: Changing the concentration of reactants or products can shift the equilibrium.

### Step 3: Identify the Factor That Does Not Affect Yield
Among the factors mentioned above, a catalyst is the one that does not alter the yield of NH3 at equilibrium. A catalyst speeds up the rate of reaction by lowering the activation energy but does not change the position of equilibrium or the concentrations of reactants and products at equilibrium.

### Conclusion
The factor that does not alter the yield of NH3 at equilibrium is the **catalyst**.

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