A fixed mass of helium gas is made to undergo a process in which its pressure varies linearly from 1 kPa to 2 kPa, in relation to its volume as the latter varies from 0.2 m³ to 0.4 m³. The heat absorbed by the gas will be : 

1200 J

\(\Delta W = \frac{1}{2} (1 + 2) * 10^3\) N/m² x (0.4 - 0.2) m³

  = 300 J

\(\Delta U = n C_v \Delta T\)

  = \(\frac{P_2V_2 - P_1V_1}{\gamma - 1}\)

\(\Rightarrow \Delta U = \frac{3}{2} (0.4 * 2 - 0.2*1) * 103 J\)

  = 900 J

\(\Delta Q = \Delta W + \Delta U\)

  = 1200 J