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MHT CET202619 April 2026Morning ShiftChemistryThermodynamics (C)Actual

A gas absorbs 120 J of heat and expands by 300 10⁻⁶ m ^3 against a constant external pressure of 2 10^5 Nm ⁻² . What will be the change in internal energy of the system ?

Options

  1. A180 J
  2. B240 J
  3. C120 J
  4. D60 J

Correct answer

D. 60 J

Step-by-step solution

Heat absorbed by the gas, q = +120 J Work done by the gas during expansion against constant external pressure is given by W = -P_ ext V Substituting the given values: W = -(2 10^5 Nm ⁻²) (300 10⁻⁶ m ^3) W = -60 J According to the first law of thermodynamics: U = q + W U = 120 J - 60 J = 60 J

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