Isothermal expansion of an ideal gas
An ideal gas expands isothermally. Which statement is true?
Answer A: explanation for every choice
A
Correct. An ideal gas's internal energy depends only on temperature, so at constant temperature, Q = W.
B
ΔU is zero, not equal to the work.
C
No heat exchange describes an adiabatic process.
D
Temperature is constant by definition in an isothermal process.
TakeawayIdeal gas, isothermal: ΔU = 0, so Q = W.
Equation usedFirst law of thermodynamics
Next question →Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID cp73.