\[
\begin{aligned}
93 \, \text{cm} \times 48 \, \text{cm} & = \boxed{4500 \, \text{cm}^2} \\
688.72 \, \text{mol} \div 83.81 \, \text{L} & = \boxed{8.217 \, \frac{\text{mol}}{\text{L}}} \\
207.6 \, \text{mol} \div 61.14 \, \text{L} & = \boxed{3.396 \, \frac{\text{mol}}{\text{L}}}
\end{aligned}
\]