163- In the figure below, a piston of 87cm is attached outside the tube from mercury. Under conditions where the air pressure is 75cmHg and the gas temperature is $27^\circ\text{C}$, the mercury column height in the tube is 72cm. As the air pressure increases upward, the gas temperature rises to $47^\circ\text{C}$. We bring the mercury column back to 72cm. How has the air pressure changed?
[(1)] The mercury level has decreased by 2 millimeters.
[(2)] The mercury level has increased by 2 millimeters.
[(3)] The mercury level has decreased by 0.2 millimeters.
[(4)] The mercury level has increased by 0.2 millimeters.
[Figure: A closed tube containing gas with a mercury column of height 87cm, open at the bottom]
\textbf{163-} In the figure below, a piston of 87cm is attached outside the tube from mercury. Under conditions where the air pressure is 75cmHg and the gas temperature is $27^\circ\text{C}$, the mercury column height in the tube is 72cm. As the air pressure increases upward, the gas temperature rises to $47^\circ\text{C}$. We bring the mercury column back to 72cm. How has the air pressure changed?
\begin{itemize}
\item[(1)] The mercury level has decreased by 2 millimeters.
\item[(2)] The mercury level has increased by 2 millimeters.
\item[(3)] The mercury level has decreased by 0.2 millimeters.
\item[(4)] The mercury level has increased by 0.2 millimeters.
\end{itemize}
\textit{[Figure: A closed tube containing gas with a mercury column of height 87cm, open at the bottom]}
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