According to Boyle's law, when the temperature is constant, the initial pressure multiplied by the initial volume is equal to the final pressure multiplied by the final volume. Mathematically, P1V1 = P2V2, where P1 and V1 are the initial pressure and volume, and P2 and V2 are the final pressure and volume, respectively. Using the given values:
(2.0 atm) * (4.0 L) = (1.0 atm) * (V2)
Solving for V2:
V2 = (2.0 atm * 4.0 L) / (1.0 atm) = 8.0 L