Consider the reaction given below. In which cases will the reaction proceed toward right by increasing the pressure ?

Options

A. `4HCl(g)+O_(2)(g)rarr2Cl_(2)(g)+2H_(2)O(g)`
B. `Cl_(2)(g)+H_(2)O(g)rarr2HCl(g)+1/2O_(2)(g)`
C. `CO_(2)(g)+4H_(2)(g)rarrCH_(4)(g)+2H_(2)O(g)`
D. `N_(2)(g)+O_(2)(g)rarr2NO(g)`

Answer

To determine in which cases the reaction will proceed to the right upon increasing the pressure, we can apply Le Chatelier's principle. This principle states that if the pressure of a system at equilibrium is increased, the equilibrium will shift in the direction that has fewer moles of gas.

Let's analyze each reaction step by step:

### Step 1: Analyze the First Reaction
**Reaction:** 4 HCl(g) + O2(g) ⇌ 2 Cl2(g) + 2 H2O(g)

- **Total moles of reactants:** 4 (HCl) + 1 (O2) = 5 moles
- **Total moles of products:** 2 (Cl2) + 2 (H2O) = 4 moles

**Conclusion:** Since the number of gaseous moles of products (4) is less than that of reactants (5), increasing pressure will shift the equilibrium to the right.

### Step 2: Analyze the Second Reaction
**Reaction:** Cl2(g) + H2(g) ⇌ 2 HCl(g) + 0.5 O2(g)

- **Total moles of reactants:** 1 (Cl2) + 1 (H2) = 2 moles
- **Total moles of products:** 2 (HCl) + 0.5 (O2) = 2.5 moles

**Conclusion:** The number of gaseous moles of products (2.5) is greater than that of reactants (2). Therefore, increasing pressure will shift the equilibrium to the left.

### Step 3: Analyze the Third Reaction
**Reaction:** CO2(g) + 4 H2(g) ⇌ CH4(g) + 2 H2O(g)

- **Total moles of reactants:** 1 (CO2) + 4 (H2) = 5 moles
- **Total moles of products:** 1 (CH4) + 2 (H2O) = 3 moles

**Conclusion:** The number of gaseous moles of products (3) is less than that of reactants (5). Thus, increasing pressure will shift the equilibrium to the right.

### Step 4: Analyze the Fourth Reaction
**Reaction:** N2(g) + O2(g) ⇌ 2 NO(g)

- **Total moles of reactants:** 1 (N2) + 1 (O2) = 2 moles
- **Total moles of products:** 2 (NO) = 2 moles

**Conclusion:** The number of gaseous moles of products (2) is equal to that of reactants (2). Therefore, increasing pressure will have no effect on the position of equilibrium.

### Final Summary
The reactions that will proceed to the right upon increasing pressure are:
- **First Reaction:** 4 HCl + O2 ⇌ 2 Cl2 + 2 H2O (correct)
- **Third Reaction:** CO2 + 4 H2 ⇌ CH4 + 2 H2O (correct)