Question

The latent heat of vaporization of water is $2240\text{J/g}$. If the work done in the process of expansion of $1\text{g}$ is $168\text{J}$, then increase in internal energy is

• A. $2408\text{J}$
• B. $2240\text{J}$
• C. $2072\text{J}$
• D. $1904\text{J}$

Answer 1

The correct option is C $2072\text{J}$

$\Delta Q=\Delta U+\Delta W$
$\because \Delta Q=mL$ $(m=1gram)$
$\begin{array}{cc}2240& =\Delta U+168\\ \Delta U& =2240-168\\ & =2072J\end{array}$