A compound of X and Y has the empirical formula XY₂. It's vapour density is equal to it's empirical formula weight. Determine it's molecular formula.

Empirical formula = XY₂

Empirical formula weight = V.D.

Molecular weight = 2 x V.D.

$\text{n} = \dfrac{\text{Molecular weight}}{\text{Empirical formula weight}} \\[0.5em] \text{n} = \dfrac{\text{2 x V.D.}}{\text{V.D.}} \\[0.5em] \text{n} = 2$

∴ Molecular formula = n[E.F.] = 2[XY₂] = X₂Y₄