Hydrolysis of $DDT$ is a first order reaction,its half-life is $10 \ years$. Time required to hydrolyse $10 \ g$ of $DDT$ to half is ......... $years$.

$A$ first-order reaction decomposes such that the time taken for $1/8$ and $1/10$ of the initial concentration to decompose are $t_{1/8}$ and $t_{1/10}$ respectively. Find the value of $\frac{t_{1/8}}{t_{1/10}} \times 10$. (Given: $\log_{10} 2 = 0.3$)

If the concentration is expressed in $mol \ L^{-1}$,the unit of the rate constant for a first-order reaction is........

$A$ first order reaction has a rate constant $0.00813 \ min^{-1}$. How long will it take for $60 \%$ completion (in $min$)?

For a reaction,$r = k[A]$. If $50 \%$ of $A$ is decomposed in $120 \ \text{minutes}$,the time taken for $90 \%$ decomposition of $A$ is $............ \ \text{minutes}$.

The decomposition of the smog component peroxyacetyl nitrate $(PAN)$ follows a first-order reaction into peroxyacetyl radical and $NO_{2(g)}$,with a half-life of $32 \ min$.
$CH_3COONO_2 \to CH_3COO^{\bullet} + NO_2$
If the initial concentration of $PAN$ in an air sample is $5.0 \times 10^{14} \ molecules/L$,what will be the concentration after $1.5 \ hr$?