AP EAPCET 24-Aug-2021 Shift 1 Paper

Given that, heat released, ΔQ=−30J
Work done on the gas, ΔW=−18J
Change in internal energy =ΔU
Initial internal cnergy, Ui=60J
Let final internal energy, Uf=U
By using first law of thermodynamics,
ΔQ=ΔW+ΔU
Substituting the values, we get
−30=−18+(Uf−Ui)
−30+18=U−60
⇒U=48J
Hence, the final internal energy of gas is 48J.