JEE Main 2026 — Thermodynamics Question with Solution
JEE Main 2026 (08 April Shift 2)
Question
One mole of diatomic gas having rotational modes only is kept in a cylinder with a piston system. The cross-section area of the cylinder is cm. The gas is heated slowly to raise the temperature by C during which the piston moves by mm. The amount of heat supplied to the gas is ________ J. (Atmospheric pressure kPa, J/mol·K) (Neglect mass of the piston)
Choose an option
Show full solutionCorrect option: B
Correct answer
B
Step-by-step explanation
Using the first law of thermodynamics:
Since the gas is diatomic with rotational modes only, the degrees of freedom are , so:
For and :
Work done by the gas:
Cross-sectional area of the piston:
Piston displacement:
Change in volume:
With :
Therefore, the heat supplied is:
Hence, the heat supplied to the gas is .
Since the gas is diatomic with rotational modes only, the degrees of freedom are , so:
For and :
Work done by the gas:
Cross-sectional area of the piston:
Piston displacement:
Change in volume:
With :
Therefore, the heat supplied is:
Hence, the heat supplied to the gas is .
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This is a previous-year question from JEE Main 2026, covering the Thermodynamics chapter of Physics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.