For a first-order reaction A `rarr` Products, the concentration of A changes from 0.1 M to 0.025 M in 40 min. The rate of the reaction when the concentration of A is 0.01 M is

Options

A. `1.73xx10^(-5) M min^(-1)`
B. `3.47 xx10^(-4) M min^(-1)`
C. `3.47 xx10^(-5) M min^(-1)`
D. `1.73 xx10^(-4) M min^(-1)`

Answer

B

Explanation

Using expression of rate constant for first order reaction we have `k=(2.303)/(t) log [A]_(0)/[A]`
Therefore `k=(12.303)/(40) log (0.1)/(0.25)=0.03465 min^(-1)`
Now rate =k[A] =`0.03465 xx0.01 =3.47 xx10^(-4) M min^(-1)`