During an adiabatic process, the pressure of a gas is found to be proportional to the cube of its temperature. The ratio of CpCυ for the gas is

P∝T3PT3= constant       ---(i)For an adiabatic process,PTγ/1−γ=constant        ---(ii)Comparing (i) and (ii), we getγ1−γ=−3 γ=−3+3γ −2γ=−3    or   γ=32 As γ=CpCυ    ∴  CpCυ=32