For the reaction

$$ \mathrm{N}_{2(\mathrm{~g})}+3 \mathrm{H}_{2(\mathrm{~g})} \longrightarrow 2 \mathrm{NH}_{3(\mathrm{~g})} $$

$\mathrm{N}_{2(\mathrm{~g})}$ disappears at the rate of $2 \times 10^{-4} \mathrm{~mol} \mathrm{dm}^{-3} \mathrm{~s}^{-1}$. Find the rate of $\mathrm{NH}_3$ formation.

Half life of a first order reaction is 3 hours. Calculate the value of $\frac{[\mathrm{A}]_0}{[\mathrm{~A}]_{\mathrm{t}}}$ after 8 hours.

$60 \%$ of a first order reaction is completed in 60 minute. What is the time taken by reactant to decompose half of its original amount?

Consider the reaction

$$ 3 \mathrm{I}_{(\mathrm{aq})}^{-}+\mathrm{S}_2 \mathrm{O}_{8(\mathrm{aq})}^{--} \longrightarrow \mathrm{I}_{3(\mathrm{aq})}^{-}+2 \mathrm{SO}_{4(\mathrm{aq})}^{2-} $$

rate of formation of $\mathrm{SO}_4^{2-}$ at a particular time is

$$ 2.2 \times 10^{-2} \mathrm{~mol} \mathrm{dm}^{-3} \mathrm{~s}^{-1} $$

What is the value of $\frac{d}{d t}\left[I_3^{-}\right]$?