AIIMS 2019 Physics First Law of Thermodynamics MCQ Question

To determine the change in internal energy (ΔU) of the system, we apply the first law of thermodynamics, which states that ΔU = Q - W, where Q is the heat added to the system and W is the work done by the system. Here, the system receives 300 calories of heat, which converts to joules as follows: Q = 300 cal × 4.18 J/cal = 1254 J. The work done by the system is 600 J, so ΔU = 1254 J - 600 J = 654 J, making option A correct. Other options are incorrect as they do not accurately reflect the calculations based on the first law of thermodynamics.