Question

Find the external work done by the system in kcal, when $20$ kcal of heat is supplied to the system the increase in the internal energy is $8400J(J=4200J/kcal)$

• A. $22kcal$
• B. $18kcal$
• C. $20kcal$
• D. $19kcal$

Answer 1

The correct option is A $22kcal$

$\begin{array}{c}Weknow,\\ \Delta d=v+\Delta w\\ \Delta d=-20\times 4200J\\ \Delta w=-84000-8400=-92400J\end{array}$

External work done $=22$k cal

Option $A$ is correct.