Given: Initial temperature (T1)=273K; Initial volume (V1)=V; Final volume (V2)=81V and γ=1.25
We know that under adiabatic condition T1V1γ−1 =T2V2γ−1 or T2273=(V1V2)1−1=(V81V)125−1=(81)0⋅25=3 or T2=3273=91K=−182∘C
(where T2 is the final temperature of the gas).