$(1)$
\[
\begin{align}
10.0\,\rm{kgf/\,\rm{cm}}^2&=10.0\times\frac{9.807}{(10^{-2})^2}\hspace{15px}\frac{N}{m^2}\\
&=9.81\times10^5\,\rm{Pa}\\
&=981\,\rm{kPa}
\end{align}
\]
$(2)$
\begin{align}
300\,\rm{mmHg}=\frac{300}{760}\times0.1013\,\rm{MPa}&=0.039986\,\rm{MPa}\\
&=40.0\,\rm{kPa}
\end{align}
$(3)$
\begin{align}
3.0\,\rm{atm}=3\times0.1013\,\rm{Mpa}&=0.3039\,\rm{MPa}\\
&=304\,\rm{kPa}
\end{align}
$(4)$
\begin{align}
200\,\rm{PS}=200\times0.7355\,\rm{kW}&=147.1\,\rm{kW}\\
&=147\,\rm{kW}
\end{align}
$(5)$
\begin{align}
9.0\,\rm{P}=9.0\times\frac{10^{-3}}{10^{-2}}\,\rm{kg/m\cdot s}=0.9\,\rm{Pa\cdot s}
\end{align}
