In a compound with molecular formula X2Y3, the valencies of Y and X are

The valency of X is 3 and the valency of Y is 2.

The valency is more simply defined as the combining power of an element. We can see the valency of an element from the subscript of the other atom in the compound. This will now serve as our guide in decoding the valencies of X and Y.

Hence, the valency of X is 3 and the valency of Y is 2.

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In a compound with molecular formula ,the valency of Y and X are 2 and 3 respectively.

Explanation:

For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.  

The given compound is where X and Y combine and their oxidation states or valencies are exchanged and written in simplest whole number ratios. Thus the oxidation state or valency of X is 3 and that of Y is 2.

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