$A$ Carnot engine with efficiency $50\%$ takes heat from a source at $600\text{ K}$. To increase the efficiency by $20\%$, keeping the temperature of the sink the same, the new temperature of the source will be: (in $\text{ K}$)

$A$ Carnot engine operates between a source and a sink. The efficiency of the engine is $40 \%$ and the temperature of the sink is $27^{\circ} C$. If the efficiency is to be increased to $50 \%$,then the temperature of the source must be increased by: (in $K$)

$A$ frictionless heat engine can be $100 \%$ efficient only if its exhaust temperature is ............

$A$ Carnot engine takes $300$ calories of heat from a source at $500 \,K$ and rejects $150$ calories of heat to the sink. The temperature of the sink is (in $\,K$)

Even a Carnot engine cannot give $100\%$ efficiency because we cannot

$A$ Carnot engine absorbs heat from a reservoir maintained at temperature $1000 \,K$. The engine rejects heat to a reservoir whose temperature is $T$. If the magnitude of absorbed heat is $400 \,J$ and work performed is $300 \,J$, then the value of $T$ is (in $\,K$)