PhysicsJEE Main 23 Jan 2026, Shift 2·Q1·MCQ·Moderate

Thermodynamics · Laws of thermodynamics

The internal energy of a gas is 3nRT. One mole of this gas is kept in a cylinder having internal cross section area of

17\ \mathrm{cm^2}

and fitted with a light movable frictionless piston. The gas is heated slowly by supplying 126 J heat. If the temperature rises by

4\ ^\circ

C, then the piston will move cm.
(atmospheric pressure

= 10^{5}

Pa)

(1)14.5
(2)1.55
(3)15.5
(4)1.45

We corrected a printing error in the original paper

Source printed “The internal energy of a monoatomic gas is 3nRT. One mole of helium is kept”; corrected to the intended “The internal energy of a gas is 3nRT. One mole of this gas is kept” (a monoatomic gas has $U = \tfrac32 nRT$ , which gives 44.8 cm, no option; the key 15.5 uses $U = 3nRT$ ); “suppling”.

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Thermodynamics · Laws of thermodynamics

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