The correct option is C 0.24 mol
As the gas leaks out, the volume and the temperature of the remaining gas do not change.
The number of moles of the gas in the vessel is given by n=PVRT
The number of moles in the vessel before the leakage isn1=P1VRT
and that after the leakage is n2=P2VRT
∴ The amount of Gas leaked is
n1−n2=(P1−P2)VRT=(210−135)×8×10−38.3×300=0.24