$A$ Carnot engine whose heat sink is at $27^{\circ} C$ has an efficiency of $40 \%$. By how much should its source temperature be changed so as to increase its efficiency to $60 \% (in $K$)?$

In a Carnot engine,the temperature of the sink is $27 \, ^\circ C$ and the temperature of the source is $927 \, ^\circ C$. If the work done by the engine to reject heat from the source to the sink is $12.6 \times 10^{6} \, J$,what is the heat absorbed from the source?

Under which ideal condition does the efficiency of a Carnot engine become $100 \%$?

If a Carnot engine works between $127^{\circ} C$ and $527^{\circ} C$,then its efficiency is ...... $\%$

$A$ Carnot engine working between $400\, K$ and $800\, K$ has a work output of $1200\, J$ per cycle. The amount of heat energy supplied to the engine from the source in each cycle is ........... $J$

$A$ Carnot engine with its cold body at $17\,^{\circ}C$ has $50\%$ efficiency. If the temperature of its hot body is now increased by $145\,^{\circ}C$,the efficiency becomes...... $\%$