Work done by gas in adiabatic process, ∆W=+83J As in adiabatic process, ∆Q=0, By first law of thermodynamics, ∆Q=∆U+∆W ⇒0=∆U+∆W ⇒∆U=−∆W so change in internal energy of gas, ∆U=−83J Also, ∆U=nCV∆T=83 Here, n=1 mole ⇒ specific heat at constant volume CV=Cp−R ⇒CV=