The efficiency of a Carnot engine operating between reservoirs maintained at temperatures $27^{\circ}C$ and $-123^{\circ}C$ is ...... $\%$

$A$ Carnot heat engine has an efficiency of $50 \%$. The temperature of the sink is maintained at $500 \ K$. To increase the efficiency up to $80 \%$, the required increment in the source temperature is: (in $K$)

$A$ reversible engine converts one-sixth of the heat input into work. When the temperature of the sink is reduced by $62^\circ C$,the efficiency of the engine is doubled. The temperatures of the source and sink are:

An engine is supposed to operate between two reservoirs at temperatures $727^oC$ and $227^oC$. The maximum possible efficiency of such an engine is:

$A$ 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 ..... $K$.

The efficiency of a Carnot engine is found to increase from $25 \%$ to $40 \%$ on increasing the temperature $(T_1)$ of the source alone by $100 \ K$. The temperature $(T_2)$ of the sink is given by: (in $K$)