Which statements about thermodynamic processes and heat engines is/are correct? 1. Work done in irreversible expansion is greater than in quasi-static expansion. 2. Efficiency of an ideal heat engine depends only on reservoir temperatures. 3. Heat flows from cold to hot only with external work.
2 and 3 only
Statement 1 — FALSE. For a gas expanding between the same two states, the work done is maximum in a quasi-static (reversible) process and less in an irreversible expansion. So work in irreversible expansion is smaller, not greater.
Statement 2 — TRUE. The efficiency of an ideal (Carnot) heat engine is \(\eta = 1 - \dfrac{T_C}{T_H}\), which depends only on the absolute temperatures of the cold (\(T_C\)) and hot (\(T_H\)) reservoirs.
Statement 3 — TRUE. By the Second Law of Thermodynamics (Clausius statement), heat cannot flow spontaneously from a colder body to a hotter body; transfer in that direction requires external work, as in a refrigerator or heat pump.
Hence statements 2 and 3 are correct → option B.
Important Questions from Heat and Transfer
The brightness of a star depends on its
Thermocouple is a device which converts
To change a temperature on the Kelvin scale to the Celsius scale, you have to ________ the given temperature.
Ramu mixes 2 litres of water at 100°C and 18 litres of water at 32°C. What temperature will the water have after mixing?
Which one of the following is the correct relation between the Kelvin temperature (T) and the Celsius temperature (tc)?
