Q. The values of dissociation constant of bases are given below. Which is the weakest base?
A) $1.8 \times 10^{- 5}$
B) $4.8 \times 10^{- 10}$
C) $7.2 \times 10^{- 11}$
D) $7.07 \times 10^{- 7}$
Explanation
(c)
For base $BOH$
$BOH \rightleftharpoons B^{+} + OH^{-}$
Dissociation constant $K_{b} = \frac{\left\lbrack B^{+} \right\rbrack\left\lbrack OH^{-} \right\rbrack}{\lbrack BOH\rbrack}$
$\therefore$ Higher the value of $K_{b}$, more will be dissociation of base and stronger will be base and vice-versa.
$\therefore$ Weakest base among given choices is having $K_{b} = 7.2 \times 10^{- 11}$.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.