Question

The formula of calcium dihydrogen phosphate is

• A. CaH₂PO₄
• B. Ca(HPO₄)₂
• C. Ca(H₂PO₄)₂
• D. Ca₃(PO₄)₂

Answer 1

The correct option is C

Ca(H₂PO₄)₂

Explanation for the correct option:

Symbol of Calcium is Ca and its valency is 2

Symbol of dihydrogen phosphate is H₂PO₄ and its valency is 1

Using criss-cross method, where the valency of cation is transposed with the valency of anion

And written as the subscript on the symbol.

The formula comes out to be Ca(H₂PO₄)₂

Explanation for the incorrect options:

CaH₂PO₄ -In this formula, valency of calcium is taken as 1 which is incorrect.

Ca(HPO₄)₂ -In this formula, symbol of hydrogen phosphate (HPO₄) is used instead of dihydrogen phosphate which is incorrect.

Ca₃(PO₄)₂ -In this formula, symbol of phosphate (PO₄) is used instead of dihydrogen phosphate which is incorrect.

Hence option (c) is correct.