We consider a thermodynamic system. If Δ U is the increase in internal energy and W is the work done by the system, which one of the following statement is true? (a) Δ U = -W in an adiabatic process (b) Δ U = W in an isothermal process (c) Δ U = -W in an isothermal process (d) Δ U = W in an adiabatic process

Answer: (a). First law: Q = Δ U + W. Adiabatic: Q = 0 ⇒ Δ U = -W. Isothermal (ideal gas): Δ U = 0, so neither (b) nor (c) holds in general. So the answer is (a).

We consider a thermodynamic system. If Δ U is the increase in… | MHT CET 2026 (15 May, Shift 1)

Q1MHT CET 2026 · 15 MAY · SHIFT 1Easy

Thermodynamic Processes

We consider a thermodynamic system. If $\Delta U$ is the increase in internal energy and $W$ is the work done by the system, which one of the following statement is true?

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Answer: (a)

First law: $Q = \Delta U + W$ .
Adiabatic: $Q = 0 \Rightarrow \Delta U = -W$ .
Isothermal (ideal gas): $\Delta U = 0$ , so neither (b) nor (c) holds in general.
So the answer is (a).

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