A number of Carnot engines are operated at identical cold reservoir temperatures $$(T_L)$$. However, their hot reservoir temperatures are kept different. A graph of the efficiency of the engines versus hot reservoir temperature $$(T_H)$$ is plotted. The correct graphical representation is

A gas mixture contains monoatomic and diatomic molecules of 2 moles each. The mixture has a total internal energy of (symbols have usual meanings)

A sphere, a cube and a thin circular plate all of same material and same mass initially heated to same high temperature are allowed to cool down under similar conditions. Then, the

In an adiabatic expansion of an ideal gas the product of pressure and volume