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PhysicsJEE Main 5 Apr 2026, Shift 1·Q7·MCQ·Easy–moderate

Thermodynamics · Laws of thermodynamics

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R

Assertion A : Change in internal energy of a system containing nn mole of ideal gas can be written as ΔU=nCv(Tf−Ti)=nRγ−1(Tf−Ti)\Delta U = nC_v(T_f - T_i) = \dfrac{nR}{\gamma - 1}(T_f - T_i), where γ=CPCv\gamma = \dfrac{C_P}{C_v}, TiT_i = initial temperature, TfT_f = final temperature.

Reason R : Relation between degree of freedom ff and γ (=Cp/Cv)\gamma\ (= C_p/C_v) is (γ=1+2f)\left(\gamma = 1 + \dfrac{2}{f}\right)

Choose the correct answer from the options given below

  1. (1)Both A and R are true and R is the correct explanation of A
  2. (2)Both A and R are true but R is NOT the correct explanation of A
  3. (3)A is true but R is false
  4. (4)A is false but R is true
We corrected a printing error in the original paper

Source labelled the two statements “Statement I” and “Statement II” (the lead-in and options use Assertion A / Reason R); source printed “ttue” in option (4).

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