Question

An ideal gas expands isothermally along ab and does 600 J of work. During the process :-

• A. The heat rejected by the gas to the surroundings is 600 J
• B. The heat absorbed by the gas from the surroundings is 600 J
• C. No heat exchange between gas and its surroundings takes place
• D. The heat absorbed by the gas is less than 600 J

Answer 1

Answer: (B)

The heat absorbed by the gas from the surroundings is 600 J

Answer 2

For an ideal gas undergoing an isothermal process, the change in internal energy ($\Delta U$) is zero because internal energy depends only on temperature, and temperature is constant. According to the First Law of Thermodynamics ($\Delta U = Q - W$), if $\Delta U = 0$, then $Q = W$. Given that the gas does 600 J of work ($W = +600 \text{ J}$), the heat absorbed by the gas ($Q$) must also be 600 J.