Discussion Forum

 One mole of diatomic ideal gas undergoes a cyclic process ABC as shown in figure. The process BC is adiabatic. The temperature at A, B and C are 400K, 800K, and 600K. respectively, Choose the correct statement 

Answer:

Explanation:

According  to first law  of thermodynamics, we get

(i) Change in internal energy from A to B. i.e, $\triangle U_{AB}$

        $\triangle U_{AB}=nC_{V}(T_{B}-T_{A})$

  $=1\times \frac{5R}{2}(800-400)=1000R$

  (ii) Change  in internal energy from B to C

   $\triangle U_{BC}=nC_{V}(T_{C}-T_{B})$

  $=1\times \frac{5R}{2}(600-800)=-500R$

  (iii)  $\triangle U_{isothermal}=0$

(iv)   Change in internal energy from C to A i.e,   $\triangle U_{CA}$

    $\triangle U_{CA}=nC_{V}(T_{A}-T_{C})$

    =   $1\times\frac{5R}{2}(400-600)=-500R$