Q. The concentration of a reactant X decreases from 01 M to 0.005 m in 40 min. If the reaction follows first order kinetics, the rate of the reaction when the concentration of X is 0.01 M will be
A) $1.73 \times 10^{- 4}Mmin^{- 1}$
B) $3.47 \times 10^{- 4}Mmin^{- 1}$
C) $3.47 \times 10^{- 5}M\ min^{- 1}$
D) $7.5 \times 10^{- 4}M\ min^{- 1}$
Explanation
(d)
$k = \frac{2.303}{t}\log\frac{A_{0}}{A}$
$= \frac{2.303}{t}\log\frac{0.1}{0.005}$
$= \frac{2.303}{t}log20 = 0.075$
Rate of reaction when concentration of X is 0.01 M will be
$0.075 \times 0.01 = 7.5 \times 10^{- 4}min^{- 1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.