$\therefore \,\,\,\,\frac{1}{2}\,\,\,\frac{{d[N{O_2}]}}{{dt}}\,\,\, = \,\, - \,\,\frac{{(0.28\,\, - \,\,0.46)}}{{30}}$
$\therefore \,\,\,\frac{1}{2}\,\,\,\frac{{d[N{O_2}]}}{{dt}}\,\,\,\, = \,\,6\,\, \times \,\,{10^{ - 3}}$
$\frac{{d[N{O_2}]}}{{dt}}\,\,\, = \,\,1.2\,\, \times \,\,{10^{ - 2}}\,\,atm\,\,{\min ^{ - 1}}$