Chemistry - GOC Question with Solution | TestHub

The conjugate bases are $\mathrm{N}{\mathrm{H}}_2^{-}$, $\mathrm{O}{\mathrm{H}}^{-}$, ${\mathrm{F}}^{-}$ and $\mathrm{C}{\mathrm{l}}^{-}$. $\mathrm{N}{\mathrm{H}}_2^{-}$, $\mathrm{O}{\mathrm{H}}^{-}$, ${\mathrm{F}}^{-}$ are in the same period, so electronegativity gives the stability order $\mathrm{N}{\mathrm{H}}_2^{-}$ $<$ $\mathrm{O}{\mathrm{H}}^{-}$ $<$ ${\mathrm{F}}^{-}$ : $\mathrm{N}{\mathrm{H}}_3$ $<$ ${\mathrm{H}}_2\mathrm{O}$ $<$ $\mathrm{HF}$. $\mathrm{C}{\mathrm{l}}^{-}$ is far larger than ${\mathrm{F}}^{-}$ and disperses the charge better, so $\mathrm{HCl}$ is the strongest acid. Order : $\mathrm{N}{\mathrm{H}}_3(1)$ $<$ ${\mathrm{H}}_2\mathrm{O}(2)$ $<$ HF(3) $<$ HCl(4).