In a Carnot engine,if the work done during isothermal expansion is $25 \%$ more than the work done during isothermal compression,then the efficiency of the engine is: (in $\%$)

In a Carnot engine,the work done by the working substance is equivalent to:

Efficiency of a heat engine whose sink is at temperature of $300 \,K$ is $40 \%$. To increase the efficiency to $60 \%$, keeping the sink temperature constant, the source temperature must be increased by (in $\,K$)

The Carnot cycle is plotted on a $P-V$ graph. Which portion represents an isothermal expansion?

$A$ Carnot engine operating between two reservoirs has an efficiency of $\frac{1}{3}$. When the temperature of the cold reservoir is raised by $x$,its efficiency decreases to $\frac{1}{6}$. The value of $x$,if the temperature of the hot reservoir is $99^{\circ} C$,will be $........ K$.

$A$ Carnot engine with $40\%$ efficiency takes heat at $500 \ K$. If its efficiency is to be $50\%$,then for the same exhaust temperature,the intake temperature must be ..... $K$.