Q. Which of the following base is weakest?
A) $NH_{4}OH;\ \ \ \ \ \ \ K_{b} = 1.6 \times 10^{- 6}$
B) $C_{6}H_{5}NH_{2};\ \ \ \ \ K_{b} = 3.8 \times 10^{- 10}$
C) $C_{2}H_{5}NH_{2};\ \ \ \ \ K_{b} = 5.6 \times 10^{- 4}$
D) $C_{9}H_{7}N;\ \ \ \ \ \ \ \ K_{b} = 6.3 \times 10^{- 10}$
Explanation
(b)
Basic strength $\propto$ dissociation constant of base $(K_{b})$.
So, smaller the value of $K_{b}$ weaker will be the base.
The weakest base will have smallest value of $K_{b}$.
$\because\ C_{6}H_{5}NH_{2}\$(aniline) has smallest value of $K_{b}$ .
$\therefore$ It is weakest base.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.