#### In a first order reaction, the concentration of the reactant, decreases from 0.8 M to 0.4 M in 15 minutes. The time taken for the concentration to change from 0.1 M to 0.025 M is Option 1) 30 minutes Option 2) 15 minutes Option 3) 7.5 minutes Option 4) 60 minutes.

As we learnt in

First Order Reaction -

The rate of the reaction is proportional to the first power of the concentration of the reaction

- wherein

Formula:

R            P

a                 0

a-x             x

[differentiate rate law]

Unit of

for next condition

Option 1)

30 minutes

Correct option

Option 2)

15 minutes

Incorrect option

Option 3)

7.5 minutes

Incorrect option

Option 4)

60 minutes.

Incorrect option