Given,
d1=5.46g/dm3
p1=2bar
T1=27°C=(27+273)K=300K
p2=1bar
T2=273K
d2=?

The density (d2)of the gas at STP can be calculated using the equation,
d=MpRT
d1d2=Mp1RT1Mp2RT2
d1d2=p1T2p2T1

d2=p2T1d1p1T2
=1×300×5.462×273
=3gdm-3
Hence, the density of the gas at STP will be 3 g dm-3.