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ChemistryJEE Main 28 Jan 2026, Shift 1·Q1·MCQ·Easy–moderate

Thermodynamics · Isothermal reversible expansion work

20.0 dm3^3 of an ideal gas ‘X' at 600 K and 0.5 MPa undergoes isothermal reversible expansion until pressure of the gas is 0.2 MPa. Which of the following option is correct ?

(Given: log⁡2=0.3010\log 2 = 0.3010 and log⁡5=0.6989\log 5 = 0.6989)

  1. (1)w=−9.1w = -9.1 kJ, ΔU=0\Delta U = 0, ΔH=0\Delta H = 0, q=9.1q = 9.1 kJ
  2. (2)w=9.1w = 9.1 J, ΔU=9.1\Delta U = 9.1 J, ΔH=0\Delta H = 0; q=0q = 0
  3. (3)w=+4.1w = +4.1 kJ, ΔU=0\Delta U = 0, ΔH=0\Delta H = 0; q=−4.1q = -4.1 kJ
  4. (4)w=−3.9w = -3.9 kJ, ΔU=0\Delta U = 0, ΔH=0\Delta H = 0; q=3.9q = 3.9 kJ

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See the full 28 Jan 2026, Shift 1 paper