QUESTION $1$

Consider a box model for an air shed over a city ${10}^{5}m$ on a side, with a mixing depth of $1200m.$ Winds with no $S{O}_2$blow at $4\frac{m}{s}$ against one side of the box. $S{O}_2$ is

emitted in the box at the rate of $20k\frac{g}{s}.$ If the wind blowing into the air shed has $5m\frac{g}{m}3$ of $S{O}_2$ in it$,$ and the $S{O}_2$ concentration in the air shed at $8$ am Monday is $10$

$m\frac{g}{m^3}$; estimate the concentration at noon.

A$.26mg{m}^{-3}$

B$.62mg{m}^{-3}$

C$.6\mathrm{.}2mg{m}^{-3}$

D$.2\mathrm{.}6mg{m}^{-3}$

QUESTION $2$

If $S{O}_2$ is not conservative and decays at $\frac{0\mathrm{.}23}{h}r,$ estimate its steady$-$state concentration. Assume that the wind does not contain $S{O}_2$ and the wind speed is $4\frac{m}{s}.$

A$.61mg{m}^{-3}$

B$.6\mathrm{.}1mg{m}^{-3}$

C$.1\mathrm{.}6mg{m}^{-3}$

D$.16mg{m}^{-3}$

QUESTION $3$

If the wind blowing into the air shed has $5m\frac{g}{m^3}$ of $S{O}_2$ in it$,$ it decays at $\frac{0\mathrm{.}23}{h}r,$ and the $S{O}_2$ concentration in the air shed at $8$ am Monday is $10m\frac{g}{m^3}$; estimate the

concentration at noon. Assume that the wind speed is $4\frac{m}{s}.$

A$.1\mathrm{.}78mg{m}^{-3}$

B$.17\mathrm{.}8mg{m}^{-3}$

C$.178mg{m}^{-3}$

D$.0\mathrm{.}178mg{m}^{-3}$

Ple