JEE Main 2025 Jan 28 Shift 2, Chemistry Q8: Basic Concepts of Thermodynamic

JEE Main2025Jan 28, Shift 2Chemistry

An ideal gas undergoes a cyclic transformation starting from the point A and coming back to the same point by tracing the path $A \to B \to C \to D \to A$ as shown in the three cases below.

Choose the correct option regarding $Δ U$ .

A
$Δ U$ (Case-III) $> Δ U$ (Case-II) $> Δ U$ (Case-I)
B
$Δ U$ (Case-I) $> Δ U$ (Case-II) $> Δ U$ (Case-III)
C
$Δ U$ (Case-I) $> Δ U$ (Case-III) $> Δ U$ (Case-II)
D
$Δ U$ (Case-I) $= Δ U$ (Case-II) $= Δ U$ (Case-III)

Solution

Internal energy $U$ is a state function, so its value depends only on the state of the system, not on the path taken.

In a cyclic process the system returns to its initial state, hence $\oint d U = 0$ and $Δ U_{cy c l e} = 0$ for every case.

$∴ Δ U_{(I)} = Δ U_{(I I)} = Δ U_{(I I I)} = 0$ .

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JEE Main 2025 Jan 28 Shift 2, Chemistry Q8: Basic Concepts of Thermodynamic

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