Step 1: Use Boyle's Law to calculate the new volume
Boyle’s law states that for a given amount of gas at constant temperature, the pressure and volume are inversely proportional:
\[
P_1 V_1 = P_2 V_2
\]
where:
- \( P_1 \) and \( V_1 \) are the initial pressure and volume,
- \( P_2 \) and \( V_2 \) are the final pressure and volume.
Step 2: Substitute the given values
Given:
- Initial pressure \( P_1 = 2 \, \text{atm} \),
- Initial volume \( V_1 = 10 \, \text{L} \),
- Final pressure \( P_2 = 1 \, \text{atm} \),
- Final volume \( V_2 \) is what we need to calculate.
Substitute the values into Boyle’s law:
\[
2 \times 10 = 1 \times V_2
\]
\[
V_2 = 20 \, \text{L}
\]
Answer: Therefore, the volume of the gas at 1 atm pressure and 300 K temperature is \( 20 \, \text{L} \). So, the correct answer is option (3).