In a first order reaction, the concentration of the reactant decreases form `0.8 M` to `0.4 M` in `15 min`. The time taken for the concentration to change form `0.1 M` to `0.025 M` is

Options

A. 30 min
B. 15 min
C. 7.5 min
D. 60 min

Answer

A

Explanation

`1^(st)` order reaction `0.8M rarr 0.4 M, t_(1//2) =15` m in
`0.1 M rarr 0.05 rarr 0.025M" Time required is "2xx t_(1//2)=30` min.