Question

An element X of valency 3 combines with another element Y of valency 2. What will be the formula of the compound formed ?

Answer 1

Valency of element X = 3
Valency of element Y = 2

$\begin{array}{ccc}\mathrm{Elements}:& \mathrm{X}& \mathrm{Y}\\ \mathrm{Valencies}:& 3& 2\end{array}$

Formula for the compound formed between X and Y can be worked out by crossing the valencies of the constituent elements.
Therefore, formula of the compound is X₂Y₃.