The Thermodynamic process, in which internal energy of the system remains constant is

Solution

Physics sir · 2 steps

For an ideal gas, internal energy depends only on temperature, so fix T and you have fixed U.

1. U depends on T. For an ideal gas, internal energy is U = nCᵥT. With a fixed amount of gas, U changes only when the temperature changes.

   Δ U = nCᵥ Δ T

   Process	What is held constant	Δ T	Δ U
   Isobaric	Pressure	not zero in general	not zero
   Isochoric	Volume	not zero in general	not zero
   Adiabatic	Heat exchange, Q = 0	not zero	Δ U = -W, not zero
   Isothermal	Temperature	zero	zero

2. So. Only the isothermal process keeps T constant, so Δ U = 0 and internal energy stays the same. The answer is (d).

The idea to keep. Whenever a question asks about Δ U for an ideal gas, look at the temperature. Same T means same U, whatever happens to P and V.

Answer from the NTA final answer key. Solution by PrepWiser.