Consider the following statements :
(I)An increase in pressure (caused by decrease in volume) at equilibrium results in increase in molar concentration of each gasous substances involved.
(II)An increase in pressure (caused by decrease in volume) at equilibrium results in increase in no. of moles of each gaseous substance involved.
(III)For the reaction `A(s)hArr B(g)+C(g)` at constant temperature, total pressure at equilibrium (of B(g) & C(g)) is not affected by changing the volume of container.
(IV)`H_2O(l)hArrH_2O(g)` on temperature increase K of this reaction is increased.
Tick the correct statement(s)

Options

A. (I)
B. (II)
C. (III)
D. (IV)

Explanation

To solve the question, we will analyze each statement one by one to determine whether they are correct or not.

### Step-by-Step Solution:

1. **Statement I**: "An increase in pressure (caused by decrease in volume) at equilibrium results in an increase in molar concentration of each gaseous substance involved."
- **Analysis**: According to the ideal gas law, pressure (P) is inversely proportional to volume (V) when temperature and the number of moles are constant. Therefore, if the volume decreases (leading to increased pressure), the molar concentration (which is moles/volume) of the gaseous substances will indeed increase.
- **Conclusion**: This statement is **correct**.

2. **Statement II**: "An increase in pressure (caused by decrease in volume) at equilibrium results in an increase in the number of moles of each gaseous substance involved."
- **Analysis**: When pressure is increased in a gaseous equilibrium, the system will shift towards the side with fewer moles of gas to counteract the change (Le Chatelier's principle). Therefore, the number of moles of gaseous substances does not increase; it may actually decrease.
- **Conclusion**: This statement is **incorrect**.

3. **Statement III**: "For the reaction A(s) ⇌ B(g) + C(g) at constant temperature, total pressure at equilibrium (of B(g) & C(g)) is not affected by changing the volume of the container."
- **Analysis**: The equilibrium constant Kp for the reaction is given by Kp = P_B * P_C. While the individual partial pressures may change with volume, the total pressure at equilibrium does not depend on the volume of the container at constant temperature. It remains constant as long as the system is at equilibrium.
- **Conclusion**: This statement is **correct**.

4. **Statement IV**: "H2O(l) ⇌ H2O(g) on temperature increase K of this reaction is increased."
- **Analysis**: The reaction involves a phase change from liquid to gas. For endothermic reactions (which this is, since heat is absorbed to convert liquid to gas), an increase in temperature will shift the equilibrium to the right (towards products), thus increasing the equilibrium constant K.
- **Conclusion**: This statement is **correct**.

### Final Conclusion:
The correct statements are:
- Statement I: Correct
- Statement II: Incorrect
- Statement III: Correct
- Statement IV: Correct

Thus, the correct statements are I, III, and IV.

### Summary of Correct Statements:
- I (Correct)
- III (Correct)
- IV (Correct)