A poly-atomic molecule ($$C_V = 3R,\, C_P = 4R$$, where R is gas constant) goes from phase space point $$A\ (P_A = 10^5\,\text{Pa},\ V_A = 4 \times 10^{-6}\,\text{m}$$ to point $$B\ (P_B = 5 \times 10^4\,\text{Pa},\ V_B = 6 \times 10^{-6}\,\text{m}^3)$$ to point $$C\,(P_C = 10^4\,\text{Pa},\; V_C = 8 \times 10^{-6}\,\text{m}^3).$$ A to B is an adiabatic path B and C to is an isothermal path. The net heat absorbed per unit mole by the system is :