The answer would be: 0.5L
This question can be solved using the ideal gas formula PV=nRT where
P= pressure
V= volume
n= number of molecule
R= constant
T= temperature
In this question, the temperature and number of the particle are not changed. The pressure is changed to twice amount. Since the pressure is inversely related to the volume, the volume should become half of the original.
PV=nRT
V=nRT/P
V1/V2= (nRT/P1)/(nRT/P2)
V1/V2= (1/270)/(1/540)
V1/V2= (1/1)/(1/2)
V1/V2 = 2
V1= 2V2
1L= 2V2
V2= 1/2 L