t is constant & pis decreased to1/4 of original value.
p is halved & t in kelvin is doubled
If T is constant & P is decreased to1/4 of original value then volume is increased by 4 times.
V1/V2 = P2/P1 = P/4P
V2 = 4 V1
If P is halved & T in kelvin is doubled, then volume is increased by 4 times.
Since, P1V1/T1 = P2V2/T2
V2 = T2P1V1/P2T1 = 2x2TPV1/PT = 4 V1