In a reaction,
$2\text{N}_2\text{O}_{5(g)} \rightarrow 4\,\text{NO}_{2(g)} + \text{O}_{2(g)}$
$\text{N}_2\text{O}_5$ disappears at a rate of $0.06$ mol dm$^{-3}$ s$^{-1}$
Calculate rate of formation of $\text{O}_{2(g)}$ ?

Half life of a first order reaction is $900$ second. If initial concentration of reactant is $0.08\,\text{mol dm}^{-3}$ find concentration that remains after $35$ minute ?

Consider the reaction,
$3\text{I}^-_{(aq)} + \text{S}_2\text{O}_8^{2-}{}_{(aq)} \longrightarrow \text{I}_3^-{}_{(aq)} + 2\text{SO}_4^{2-}{}_{(aq)}$
If the rate of formation of $\text{SO}_4^{2-}$ at a particular time is $2.2 \times 10^{-2}\,\text{mol dm}^{-3}\,\text{s}^{-1}$. Calculate the rate of consumption of $\text{I}^-$.

For a first order reaction, half life is $5$ hour. What time is required to reduce $10$ g of reactant to $2.5$ g ?