p-Block Elements-I 1 Question 18
18. Statement $\mathrm{IAl}(\mathrm{OH})_{3}$ is amphoteric in nature.
Statement II $\mathrm{Al}-\mathrm{O}$ and $\mathrm{O}-\mathrm{H}$ bonds can be broken with equal ease in $\mathrm{Al}(\mathrm{OH})_{3}$.
(1998, 2M)
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Answer:
Correct Answer: 18. Three centre two electron bond or banana bond.
Solution:
- Due to small size and high charge on $\mathrm{Al}$ in $\mathrm{Al}(\mathrm{OH})_{3}$ the fission ability of $\mathrm{Al}-\mathrm{O}$ and $\mathrm{O}-\mathrm{H}$ bonds become comparable and compound can give both $\mathrm{H}^{+}$and $\mathrm{HO}^{-}$under appropriate reaction conditions as:
$$ \underset{\text { Base }}{\mathrm{Al}(\mathrm{OH}){3}}+3 \mathrm{HCl} \longrightarrow \mathrm{AlCl}{3}+3 \mathrm{H}_{2} \mathrm{O} $$
$$ \mathrm{Al}(\mathrm{OH}){3}+\mathrm{NaOH} \longrightarrow \mathrm{Na}\left[\mathrm{Al}(\mathrm{OH}){4}\right] $$
Therefore, both statements are correct and statement II is a correct explanation of statement I.
