Chemistry - Ionic Equilibrium Question with Solution | TestHub

For base$\text{B}\mathrm{\text{O}}\mathrm{\text{H}}$

$\text{B}\mathrm{\text{O}}\mathrm{\text{H}}\rightleftharpoons {\text{B}}^{+}+\mathrm{\text{O}}{\mathrm{\text{H}}}^{-}$

Dissociation constant${\text{K}}_{\text{b}}=\frac{\left[{\text{B}}^{+}\right]\left[\mathrm{\text{O}}{\mathrm{\text{H}}}^{-}\right]}{\left[\text{B}\mathrm{\text{O}}\mathrm{\text{H}}\right]}$

$\therefore$Higher the value of${\text{K}}_{\text{b}}$, more will be dissociation of base and stronger will be base and vice-versa.

$\therefore$Weakest base among given choices is having${\text{K}}_{\text{b}}=7.2\times {10}^{-11}$.