Question

$\begin{array}{cc}\text{List I}& \text{List II}\\ \text{A.}B{i}^{3+}⟶(BiO{)}^{+}& \text{p. Heat}\\ \text{B.}[Al{O}_2{]}^{-}⟶Al(OH{)}_3& \text{q. Hydrolysis}\\ \text{C.}Si{O}_4^{4-}⟶S{i}_2{O}_7^{6-}& \text{r. Acidification}\\ \text{D.}\left(B_4{O}_7^{2-}\right)⟶B(OH{)}_3& \text{s. dilution by water}\end{array}$

• A. A – q B – r C – p D –q,r
• B. A – r B – q C – p D –q,r
• C. A – q,r B – q C – q D –q
• D. None of the above

Answer 1

The correct option is A

A – q B – r C – p D –q,r

$B{i}^{3+}⟶(BiO{)}^{+}$

The above is a clear, textbook example of hydrolysis. It is characteristic of $B{i}^{3+}$. We know that aluminium hydroxide (and alumina) are amphoteric. Observe this reaction of $Al(OH{)}_3$ with $NaOH$

$Al(OH{)}_3+NaOH⟶Na[Al{O}_2]+2H_{2}O$

It is in fact an equilibrium in reality. Any acidification will drive the reaction the backward direction.

Orthosilicates are converted to pyrosilicated by heating:

$Si{O}_4^{4-}⟶S{i}_2{O}_7^{6-}$

Lastly, this is acidic hydrolysis:

$N{a}_2{B}_4{O}_7+2HCl+5H_{2}O⟶2NaCl+4B(OH{)}_3$

A – q B – r C – p D –q,r