Al₂O₃ is the formula of Aluminium oxide. Write the formulae of :

(i) Aluminium nitrate

(ii) Aluminium phosphate

(i) Formula of aluminium nitrate

$\text{Al}^{3+} \phantom{\nearrow} \text{NO}${3}^{1-} \\[0.5em] \overset{\phantom{3}{3}}{\text{Al}} \space {\searrow}\mathllap{\swarrow} \space \overset{1}{\text{N}}\text{O}{3} \Rightarrow \underset{\phantom{2}{1}}{\text{Al}} \space {\searrow}\mathllap{\swarrow} \space \underset{3}{\text{N}}\text{O}_{3} \\[0.5em]

So, we get the formula as $\bold{Al}\bold{(NO}${\bold{3}}\bold{)}\bold{3}

(ii) Formula of aluminium phosphate

$\text{Al}^{3+} \phantom{\nearrow} \text{PO}${4}^{3-} \\[0.5em] \overset{\phantom{3}{3}}{\text{Al}} \space {\searrow}\mathllap{\swarrow} \space \overset{3}{\text{P}}\text{O}{4} \Rightarrow \underset{\phantom{2}{1}}{\text{Al}} \space {\searrow}\mathllap{\swarrow} \space \underset{1}{\text{P}}\text{O}_{4} \\[0.5em]

So, we get the formula as $\bold{Al}\bold{PO}_{\bold{4}}$