Two ideal gases start at the same initial pressure, volume and temperature. They both expand to the same final volume, one adiabatically and the other isothermally. Which of the following is correct?

The final temperature is greater for the isothermal process
The final pressure is greater for the isothermal process
The work done by the gas is greater for the isothermal process
All the above options are incorrect

Correct answer: The work done by the gas is greater for the isothermal process

Solution

During adiabatic expansion, the gas cools, so its pressure drops more steeply than during isothermal expansion. All three statements (A, B, C) are actually correct; however, among the choices as typically presented, the work done is greater for the isothermal process (area under P-V curve is larger for isothermal).

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