KCET 2026 Chemistry Solved Paper

Concept:The change in internal energy ($\Delta U$) depends only on the initial and final states, not on the path taken.Explanation:According to the first law of thermodynamics, $\Delta U = Q - W$, where $Q$ is heat supplied to the system and $W$ is work done by the system.For path ACB, heat added is $Q_{ACB} = 60 \, \mathrm{J}$ and work done is $W_{ACB} = 30 \, \mathrm{J}$.So, $\Delta U = 60 - 30 = 30 \, \mathrm{J}$.For path ADB, the internal energy change is the same because both paths connect states A and B.Thus, $\Delta U = 30 \, \mathrm{J}$ for path ADB as well.Given $W_{ADB} = 10 \, \mathrm{J}$, using the first law: $30 = Q_{ADB} - 10$.Therefore, $Q_{ADB} = 30 + 10 = 40 \, \mathrm{J}$.Hence, the heat flow into the system in path ADB is $40 \, \mathrm{J}$.Answer:$Q_{ADB} = 40 \, \mathrm{J}$Correct option: D. 40 J