In a closed container following equilibrium will be attained-
`A(s)+B(g)hArrAB(g)`
`B(g)+C(g)hArrBC(g)`
On adding He gas (inert) to the above system at constant pressure & temperature

Options

A. Amount of `AB(g)` will be increased surely
B. Amount of `B(g)` will be decreased surely
C. Amount of `C(g)` will be decreased surely.
D. Amount of `BC(g)` will be decreased surely.

Explanation

To solve the problem, let's analyze the situation step by step:

### Step 1: Understand the Equilibrium Reactions
We have two equilibrium reactions:
1. \( A(s) + B(g) \rightleftharpoons AB(g) \)
2. \( B(g) + C(g) \rightleftharpoons BC(g) \)

In these reactions, \( A \) is a solid, while \( B \) and \( C \) are gases, and \( AB \) and \( BC \) are also gases.

### Step 2: Identify the Effect of Adding Helium Gas
Helium gas is an inert gas, meaning it does not react with any of the substances in the equilibrium reactions. When we add helium gas to the system at constant pressure and temperature, we need to consider how this affects the system.

### Step 3: Analyze the Impact on Concentration
- The addition of helium gas increases the total pressure in the container, but since it is inert, it does not change the partial pressures of the reacting gases \( B \) and \( C \).
- The concentration of the reactants and products (\( A \), \( B \), \( C \), \( AB \), and \( BC \)) remains unchanged because the inert gas does not participate in the reactions.

### Step 4: Conclusion on Equilibrium Constant
Since the concentrations of the reactants and products remain unchanged, the equilibrium constant for both reactions will also remain the same. Therefore, the position of equilibrium does not shift.

### Final Answer:
The addition of helium gas does not affect the equilibrium concentrations of \( A \), \( B \), \( C \), \( AB \), or \( BC \). Thus, the equilibrium constant remains unchanged, and the amounts of all species involved in the reactions will neither increase nor decrease.

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