$=-\frac{1}{2} \frac{\Delta\left[\mathrm{N}_2 \mathrm{O}_5\right]}{\Delta \mathrm{t}}=\frac{1}{4} \frac{\left[\mathrm{NO}_2\right]}{\Delta \mathrm{t}}=\frac{\Delta\left[\mathrm{O}_2\right]}{\Delta \mathrm{t}}$
$\mathrm{ROR}=-\frac{1}{2} \frac{\Delta\left[\mathrm{N}_2 \mathrm{O}_5\right]}{\Delta \mathrm{t}}=-\frac{1}{2} \frac{(2.75-3)}{30} \mathrm{molL}^{-1} \mathrm{~min}^{-1}$
$\mathrm{ROR}=-\frac{1}{2} \frac{(-0.25)}{30} \mathrm{molL}^{-1} \mathrm{~min}^{-1}$
$\text { ROR }=\frac{1}{240} \mathrm{molL}^{-1} \mathrm{~min}^{-1}$
$\text { Rate of formation of } \mathrm{NO}_2=\frac{\Delta\left[\mathrm{NO}_2\right]}{\Delta \mathrm{t}}=4 \times \mathrm{ROR}$
$=\frac{4}{240}=16.66 \times 10^{-3} \mathrm{molL}^{-1} \mathrm{~min}^{-1} \simeq 17 \times 10^{-3}$

$\begin{matrix}
O\,\,\,\,\,\,\, \\
||\,\,\,\,\,\,\, \\
C{{H}_{3}}-C-OON{{O}_{2}} \\
\end{matrix}$ $\to$ $\begin{matrix}
\,\,\,\,\,\,\,\,\,\,\,O\,\,\,\,\,\,\,\, \\
\,\,\,\,\,\,\,\,\,||\,\,\,\,\,\,\, \\
C{{H}_{3}}-C-O\overset{\centerdot }{\mathop{O}}\, \\
\end{matrix}$ $ + N{O_2}$
જો હવાના નમૂનામાં $PAN$ ની શરૂઆતની સાંદ્રતા $5.0 \times 10^{14}\, molecules/L$ હોય તો $1.5\, hr$ પછી સાંદ્રતા કેટલી થશે ?