\textbf{167.} One mole of a monatomic ideal gas undergoes an isobaric process during which $J\,40$ of work is done on the surroundings. What is the change in internal energy of the gas in joules?
\begin{itemize}
\item[(1)] $150$
\item[(2)] $100$
\item[(3)] $60$
\item[(4)] $20$
\end{itemize}