The rate constant for a first order reaction is `7.5 xx 10^(-4) s^(-1)`. If initial concentration of reactant is `0.080 M`, what is the half life of reaction ?

Options

A. 990S
B. 79.2 s
C. 12375 S
D. `10.10 xx 10^(-4)` S

Answer

A

Explanation

Data:
`k = 7.0 xx 10^(-4) s^(-1),[A]_(0) = 0.080 M, t^(1//2) = ?`
solution:
For `1^(st)` order
`t^(1//2) = 0.693/k = 0.693/(7 xx 10^(-4)s^(-1)) = 0.693/7 xx 10^(-4) = 990s`