The knowledge of valencies of various radicals helps us to write the formulae of chemical compounds. The total positive charge on positive ions ( cations ) is equal to the total negative charge on negative ions ( anions) in a molecule. Therefore, in writing the formula of a compound, the positive and negative ions are adjusted in such a way that the total number of positive charges of positive ions ( cations ) becomes equal to the total number of negative charges of negative ions ( anions) . There is another simple method for writing the formulae of ionic compounds. In this method, the valencies ( or positive or negative charges ) of the ions can be 'crossed over' to give subscripts. The purpose of crossing over of charges is to find the number of ions required to equalise the number of positive and negative charges.
The formula of chloride of a metal M is `MCl_(3)`, then the formula of the phosphate of metal M will be

Options

A. `MPO_(4)`
B. `M_(2)PO_(4)`
C. `M_(3)PO_(4)`
D. `M_(2)(PO_(4))_(3)`

Answer

a

Explanation

Valency of M is 3.

`:.` The formula of phosphate of metal M will be `MPO_(4)`.