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MHT CET202522 Apr 2025Morning ShiftChemistryThermodynamics (C)Actual

Calculate the work done in joule if 2 moles of an ideal gas expand isothermally from 15.5 dm ^3 to 20 dm ^3 at constant pressure 1 atm .

Options

  1. A-456 ~J
  2. B-228 ~J
  3. C-684 ~J
  4. D-912 ~J

Correct answer

A. -456 ~J

Step-by-step solution

The work done during an isothermal expansion at constant pressure is given by W = -P_ ext V . Given V₁ = 15.5 dm ^3 and V₂ = 20 dm ^3 , the volume change is V = 20 - 15.5 = 4.5 dm ^3 . At constant external pressure P_ ext = 1 atm , the work is W = -(1)(4.5) = -4.5 atm dm ^3 . Converting to joules using 1 atm dm ^3 = 101.325 J yields W = -4.5 101.325 = -455.9625 J . Rounded to three significant figures, W -456 J , which corresponds to option A .

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