Two moles of helium gas $\left(\gamma=\frac{5}{3}\right)$ at $27^{\circ} \mathrm{C}$ is expanded at constant pressure until its volume is doubled. Then it undergoes an adiabatic change until the temperature returns to its initial value. The work done during adiabatic process is (universal gas constant $=8.3 \mathrm{~J} \mathrm{~mol}^{-1} \mathrm{~K}^{-1}$ )

• Correct answer
  A

  $7470 \mathrm{~J}$
• B

  $7070 \mathrm{~J}$
• C

  $4770 \mathrm{~J}$
• D

  $4077 \mathrm{~J}$

Hence, the correct answer is option: 'A'.