Question

The formula of the metal oxide of metal A is ${\text{A}}_{\text{2}}{\text{O}}_{\text{3}}$. Determine the formula of its phosphate.

• A. ${\text{A}}_{\text{3}}{\text{PO}}_{\text{4}}$
• B. ${\text{APO}}_{\text{4}}$
• C. ${\text{A}}_{\text{2}}{\text{(PO}}_{\text{4}}{\text{)}}_{\text{2}}$
• D. ${\text{A(PO)}}_{\text{2}}$

Answer 1

The correct option is B

${\text{APO}}_{\text{4}}$

Explanation for correct option

(B)${\text{APO}}_{\text{4}}$

Valency of metal

• Given that the formula of metal oxide is ${\text{A}}_{\text{2}}{\text{O}}_{\text{3}}$. Thus the charge of metal is $3$.

Formula of its phosphate

• The charge of the phosphate ion$({\mathrm{PO}}_4)$ is $-3$.
• $$\begin{gathered} {\text{Symbol /Formula A PO}}_{\text{4}} \\ \text{Charge +3 -3} \end{gathered}$$
• Crossover the charges of the combining atoms as follows:-
• So, the formula of its phosphate is ${\mathrm{APO}}_4$.

Explanation for incorrect option

The formula of its phosphate is ${\mathrm{APO}}_4$. Hence, the incorrect options are (A), (C), and (D) are incorrect.

Hence, option (B) is correct. The formula of its phosphate is ${\mathrm{APO}}_4$.