The GATE Grind

GATE 2026 ME – Question 28

Thermodynamics · Zeroth, first and second laws, work, heat and energy changes · 1 mark · Multiple choice

For the isothermal expansion of an ideal gas in a piston cylinder system, the net heat supplied during the process is equal to the net work. Which one of the following statements is correct for the given process?

  1. The process is possible.
  2. The process is not possible as it violates the second law of thermodynamics.
  3. The process is not possible as it violates the first law of thermodynamics.
  4. The process is possible, however, it violates the second law of thermodynamics.

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Show answer and explanation

Correct answer: (A) The process is possible.

Explanation

For an ideal gas the internal energy depends only on temperature, so in an isothermal process $\Delta U = 0$ and the heat supplied equals the work done. This is allowed, because the second law only forbids doing this in a cycle. This is a single process, so it is possible.