In first order reaction, the concentration of the reactant decreases from $0.8 \mathrm{M}$ to $0.4…
In first order reaction, the concentration of the reactant decreases from $0.8 \mathrm{M}$ to $0.4 \mathrm{M}$ in 15 minutes. The time taken for the concentration to change from $0.1 \mathrm{M}$ to $0.025 \mathrm{M}$ is
30 minutes
60 minutes
$7.5$ minutes
15 minutes
Solution
$\mathrm{t}_{1 / 2}=15$ minutes
$\therefore$ No. of half lives $s=2$
( $\therefore$ for change of $0.1$ to $0.025$ ) is 30 minutes