Question

Heat of $30kcal$ is supplied to a system and $4200J$ of external work is done on the system so that its volume decreases at constant pressure. What is the change in its internal energy. $=(J=4200J/kcal)$

• A. $1.302\times {10}^{5}J$
• B. $2.302\times {10}^{5}J$
• C. $3.302\times {10}^{5}J$
• D. $4.302\times {10}^{5}J$

Answer 1

The correct option is A $1.302\times {10}^{5}J$

$\Delta Q=30\times 4200$

$=126000J$

$\Delta W=-4200J$

$\therefore \Delta u=\Delta Q-\Delta W$

$=126000+4200J$

$=1.302\times {10}^{5}J$

Hence,

option $\left(A\right)$ is correct answer.