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MHT CET202525 Apr 2025Morning ShiftChemistryThermodynamics (C)Actual

Calculate the work done in joule if 1 mole of ideal gas is compressed from 25 dm ^3 to 13 dm ^3 at constant external pressure 4 bar.

Options

  1. A2400 J
  2. B4800 J
  3. C6000 J
  4. D7200 J

Correct answer

B. 4800 J

Step-by-step solution

Work done against constant external pressure is given by W = -P_ ext V . Given P_ ext = 4 bar with volume change V = V₂ - V₁ = 13 - 25 = -12 dm ^3 . Convert units to SI: 1 bar = 10^5 Pa , so P_ ext = 4 10^5 Pa . Volume change: 1 dm ^3 = 10⁻³ m ^3 , so V = -12 10⁻³ m ^3 . The work done becomes: W = -(4 10^5) (-12 10⁻³) = (4 10^5) (12 10⁻³) = 4800 J . This positive value indicates work is done on the system during compression. Final answer: 4800 J

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