exam11

\begin{questions}
\question[10]
Why is there air?
\question
What if there were no air?
\begin{parts}
\part[5]
Describe the effect on the balloon industry.
\part[5]
Describe the effect on the aircraft industry.
\end{parts}
\question[20]
\begin{parts}
\part
Define the universe. Give three examples.
\part
If the universe were to end, how would you know?
\end{parts}
\end{questions}