$A$ Carnot engine working between $300 \ K$ and $400 \ K$ produces $800 \ J$ of useful work. The amount of heat energy supplied to the engine from the source is: (in $J$)

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

An ideal Carnot engine,whose efficiency is $40 \%$ receives heat at $500 \; K$. If its efficiency is $50 \%$ then the intake temperature for the same exhaust temperature is ......... $K$.

In a Carnot engine,the temperature of the reservoir is $527^{\circ} C$ and that of the sink is $200 \; K$. If the work done by the engine when it transfers heat from the reservoir to the sink is $12000 \; kJ$,the quantity of heat absorbed by the engine from the reservoir is $x \times 10^{6} \; J$. Find the value of $x$.

The efficiency of a Carnot engine which operates between the two temperatures $T_{1} = 500 \ K$ and $T_{2} = 300 \ K$ is: (in $\%$)

An ideal gas heat engine operates in a Carnot cycle between $227^{\circ}C$ and $127^{\circ}C$. It absorbs $6 \times 10^4 \text{ cal}$ of heat at the higher temperature. The amount of heat converted to work is ......... $\times 10^4 \text{ cal}$.