Question

If heat absorbed by the working substance from the source is $Q_1=550\text{J}$, heat rejected to the sink is $Q_2=200\text{J}$ then work done by the working substance in a cyclic process is

• A. $250\text{J}$
  
• B. $350\text{J}$
• C. $750\text{J}$
• D. $550\text{J}$

Answer 1

The correct option is B $350\text{J}$

Heat absorbed by working substance,
$Q_1=+550\text{J}$
Heat rejected to the sink,
$Q_2=-200\text{J}$
For a cyclic process, change in internal energy $\Delta U=0$, applying first law of thermodyamics
$\Rightarrow Q=\Delta U+W...\left(i\right)$
For the cyclic process, $Q=Q_1+Q_2$
$\Rightarrow (550+(-200\left)\right)=0+W$
$\therefore W=350\text{J}$