An ideal heat engine exhausting heat at $77^{\circ}C$ is to have a $30\%$ efficiency. It must take heat at ...... $^{\circ}C$.

$A$ diatomic ideal gas is used in a Carnot engine as the working substance. During the adiabatic expansion of the cycle,if the volume of the gas increases from $V$ to $32 V$,then the efficiency of the engine is

The efficiency of a Carnot engine depends on what,and of what is it independent?

For an ideal heat engine,the temperature of the source is $127\,^{\circ} C$. In order to have $60\, \%$ efficiency,the temperature of the sink should be $........\,{ }^{\circ} C$. (Round off to the nearest integer)

$A$ 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 $J$)

The Carnot cycle (reversible) of a gas represented by a Pressure-Volume $(P-V)$ curve is shown in the diagram. Consider the following statements:
$I.$ Area $ABCD =$ Work done by the gas
$II.$ Area $ABCD =$ Net heat absorbed
$III.$ Change in the internal energy in the cycle $= 0$
Which of these are correct?