What is the theoretical efficiency of a heat engine?

State and explain Carnot's theorem.

For a Carnot engine,the efficiency is given by $W/Q_1 = 1/6$. If the temperature of the sink is reduced by $62^{\circ}C$,the efficiency doubles. The initial temperatures of the sink and the source are,respectively:

An ideal gas heat engine operates in a Carnot cycle between $227^{\circ}C$ and $127^{\circ}C$. It absorbs $6 \times 10^4 \, J$ of heat at the high temperature. The amount of heat converted into work is:

$A$ Carnot engine operates between $300 \ K$ and $600 \ K$. If the work done per cycle is $800 \ J$,then the heat supplied per cycle is ....... $J/cycle$.

$A$ Carnot engine,whose efficiency is $40\%$,takes in heat from a source maintained at a temperature of $500\ K$. It is desired to have an engine of efficiency $60\%$. Then,the intake temperature for the same exhaust (sink) temperature must be ....... $K$.