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 form 0.1 M to 0.025 M is :

Options

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

Answer

c

Explanation

The concentration of the reactants decrease from 0.8 to 0.4 in 15 min i.e., `T_(1//2) = 15` min , concentration from 0.1 m to 0.025 will fall in 2 half lives so total time taken = `2 xx T_(1//2) = 2 xx 15 = 30` min.