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JEE Main202628 January 2026Morning ShiftChemistryThermodynamics (C)Actual

20.0 dm 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: 2=0.3010 and 5=0.6989 )

Options

  1. Aw =-9.1 ~kJ , U =0, H =0, q =9.1 ~kJ
  2. Bw =+4.1 ~kJ , U =0, H =0 ; q =-4.1 ~kJ
  3. Cw =9.1 ~J , U =9.1 ~J , H =0 ; q =0
  4. Dw =-3.9 ~kJ , U =0, H =0 ; q =3.9 ~kJ

Correct answer

A. w =-9.1 ~kJ , U =0, H =0, q =9.1 ~kJ

Step-by-step solution

For isothermal reversible process U = H = 0 w_ iso = -p₁ v₁ P₁ P₂ w_ iso = -0.5 10^6 20 10⁻³ 0.5 0.2 w_ iso = -0.5 10^6 20 10⁻³ 2.303 (.6989 - .3010) w -9.1 kJ q = -w = 9.1 kJ

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