JEE Main 2026 Jan 21 Shift 2, Physics Q25: Thermodynamic Processes

JEE Main2026Jan 21, Shift 2Physics

A diatomic gas ( $γ = 1.4$ ) does 100 J of work when it is expanded isobarically. Then the heat given to the gas _________ J.

Your answer

Solution

For an isobaric process, $W = n R Δ T = 100$ J. Heat supplied: $Q = n C_{p} Δ T = (\frac{f}{2} + 1) n R Δ T$ , where $f$ is degrees of freedom.

For a diatomic gas $γ = 1.4$ gives $f = 5$ , so $C_{p} / R = \frac{7}{2}$ .

$Q = \frac{7}{2} \times n R Δ T = \frac{7}{2} \times 100 = 350$ J.

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