If one mole of a gas A (mol.wt-40) occupies a volume of 20 litres, under the same conditions of temperature and pressure the volume occupied by 2 moles of gas B (mol.wt=80) is

Options

A. 80 L
B. 60 L
C. 50 L
D. 40 L

Answer

To solve the problem, we will use the relationship between the number of moles of a gas and its volume under the same conditions of temperature and pressure, which is derived from the ideal gas law.

### Step-by-Step Solution:

1. **Understand the relationship between moles and volume**: According to the ideal gas law (PV = nRT), the volume (V) of a gas is directly proportional to the number of moles (n) when the temperature (T) and pressure (P) are constant.

2. **Identify the volume occupied by gas A**: We are given that 1 mole of gas A occupies a volume of 20 liters. Therefore, we can express this as:
\[ V_A = 20 \text{ liters} \quad \text{for} \quad n_A = 1 \text{ mole} \]

3. **Determine the volume occupied by gas B**: We need to find the volume occupied by 2 moles of gas B. Since the volume is directly proportional to the number of moles, we can set up the following relationship:
\[ V_B = k \cdot n_B \]
where \( k \) is a constant that represents the volume occupied by 1 mole of gas under the same conditions.

4. **Calculate the volume for gas B**: Since we know that 1 mole of gas A occupies 20 liters, we can assume that gas B will occupy a similar volume per mole because they are under the same conditions of temperature and pressure. Thus:
\[ V_B = 2 \cdot V_A = 2 \cdot 20 \text{ liters} = 40 \text{ liters} \]

5. **Conclusion**: The volume occupied by 2 moles of gas B is 40 liters.

### Final Answer:
The volume occupied by 2 moles of gas B is **40 liters**.