Which statement is not correct?

Options

A. Rate of an exothermic reaction increases with temperature.
B. Solubility of `NaOH` increases with temperature.
C. `K_(p)` for `N_(2)(g)+3H_(2)(g)hArr 2NH_(3)(g)` increases with increase in pressure.
D. For gaseous reaction `2BhArr AK_(p)` is smaller than `K_(c)`.

Answer

To determine which statement is not correct, let's analyze each statement one by one based on the principles of chemical equilibrium and thermodynamics.

### Step-by-step Solution:

1. **Statement 1: Rate of exothermic reaction increases with temperature.**
- This statement is **incorrect**. For exothermic reactions, increasing the temperature generally decreases the rate of the forward reaction because the system tries to counteract the increase in temperature by favoring the endothermic direction (the reverse reaction). Therefore, this statement is not correct.

2. **Statement 2: Solubility of NaOH increases with temperature.**
- This statement is **correct**. The dissolution of NaOH in water is an endothermic process, meaning it absorbs heat. According to Le Chatelier's principle, increasing the temperature will shift the equilibrium to favor the dissolution of NaOH, thus increasing its solubility.

3. **Statement 3: Kp for the reaction 4N2 + 3H2 ⇌ 2NH3 increases with an increase in pressure.**
- This statement is **incorrect**. For the reaction, we have 7 moles of gas on the reactant side (4N2 + 3H2) and 2 moles of gas on the product side (2NH3). According to Le Chatelier's principle, increasing pressure favors the side with fewer moles of gas, which in this case is the product side. Therefore, Kp does not necessarily increase with pressure; it may shift the equilibrium position but does not imply Kp increases.

4. **Statement 4: For a gaseous reaction, 2B ⇌ A, Kp is smaller than Kc.**
- This statement is **correct**. The relationship between Kp and Kc is given by the equation Kp = Kc(RT)^(Δng), where Δng is the change in the number of moles of gas. In this case, Δng is negative (1 - 2 = -1), which means Kp will be smaller than Kc because we are multiplying Kc by a positive quantity (RT) raised to a negative power.

### Conclusion:
The statements that are not correct are **Statement 1** and **Statement 3**. However, since the question asks for which statement is not correct, we can conclude that **Statement 1** is the primary focus as it directly states a misconception about the rate of exothermic reactions.