168. An ideal gas undergoes two processes from state a to state c via state b. If the work done along this path on the gas is W, and the heat given to the gas is Q, and $\Delta U$ is the change in internal energy of the gas, what are the signs of Q, W, and $\Delta U$ respectively? [Figure: P-V diagram showing a process from point a to point b (horizontal, increasing V) then from b to c (curved, increasing P and decreasing V), labeled ``irreversible'']
[(1)] positive, zero, and positive
[(2)] positive, positive, and positive
[(3)] positive, negative, and zero
[(4)] negative, positive, and positive
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\textbf{168.} An ideal gas undergoes two processes from state a to state c via state b. If the work done along this path on the gas is W, and the heat given to the gas is Q, and $\Delta U$ is the change in internal energy of the gas, what are the signs of Q, W, and $\Delta U$ respectively?
\textit{[Figure: P-V diagram showing a process from point a to point b (horizontal, increasing V) then from b to c (curved, increasing P and decreasing V), labeled ``irreversible'']}
\begin{itemize}
\item[(1)] positive, zero, and positive
\item[(2)] positive, positive, and positive
\item[(3)] positive, negative, and zero
\item[(4)] negative, positive, and positive
\end{itemize}
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