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MHT CET202522 Apr 2025Evening ShiftChemistryThermodynamics (C)Actual

Calculate the change in internal energy of the system if 20 kJ work is done on the system and it releases 10 kJ heat in a particular reaction.

Options

  1. A20 kJ
  2. B40 kJ
  3. C10 kJ
  4. D30 kJ

Correct answer

C. 10 kJ

Step-by-step solution

The first law of thermodynamics states that the change in internal energy U of a system equals the heat added to it plus the work done on it: U = q + w . Work done on the system is positive, so w = +20~ kJ . Heat released by the system is negative, so q = -10~ kJ . Substituting into the equation: U = -10 + 20 = 10~ kJ The change in internal energy is 10 kJ .

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