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The internal energy of the air in a room of size 4 m×4 m×3 m at 1 atmosphere of pressure will be ______ ×10⁶ J. (Consider air to be a diatomic gas.)

Asked in JEE Main 2nd April 2nd Shift 2025 · Molar Specific Heats and Degrees of Freedom

Answer: 12

Step-by-step solution

Air is diatomic, so U=nC_VT=5/2nRT=5/2PV.

V=4×4×3=48 m³ and P=1.013×10⁵ Pa.

U=2.5×1.013×10⁵×48=1.216×10⁷ J =12.2×10⁶ J.

To the nearest integer, 12.

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