If a source is at a temperature $T_1$ and a sink is at a temperature $T_2$,the efficiency of the Carnot engine is maximum when

An ideal gas heat engine operates in a Carnot cycle between $227\,^{\circ}C$ and $127\,^{\circ}C$. It absorbs $6.0 \times 10^4\,cal$ at the higher temperature. The amount of heat converted into work is equal to

The temperature-entropy $(T-S)$ diagram of a reversible engine cycle is given in the figure. Its efficiency is

What is the common feature of a heat engine based on a cyclic process?

$A$ heat engine operates between a cold reservoir at temperature $T_{2} = 400 \, K$ and a hot reservoir at temperature $T_{1}$. It takes $300 \, J$ of heat from the hot reservoir and delivers $240 \, J$ of heat to the cold reservoir in a cycle. The minimum temperature of the hot reservoir has to be $.... K$.

Explain why the efficiency of a Carnot engine cannot be $100\%$?