N moles of an ideal gas undergo a two-step process as shown in the figure. Let P, V, and T denote the pressure, volume, and temperature of the gas, respectively. The gas, initially at state-1 (P₁, V₁, T₁), undergoes an isochoric (constant volume) process to reach state-A, and then undergoes an isobaric (constant pressure) expansion to reach state-2 (P₂, V₂, T₂). For an ideal gas, C_P – C_V = NR, where C_P and C_V are the heat capacities at constant pressure and constant volume, respectively, and assumed to be temperature independent. The heat gained by the gas in the two-step process is given by