An ideal gas has a volume of 3 V at 2 atmosphere pressure. Keeping the temperature constant, its pressure is doubled. The volume of the gas will be:

Initial volume V1 = 3VInitial pressure P1 = 2 atmosphereFinal pressure                   P2 = 2P1 = 2 × 2 = 4 atmosphereAccording to the Boyle's law we haveP1V1 = P2V2(where V2 is the final volume of gas)or 2 × 3V = 4×V2 or V2 = 1.5 V