The empirical formula of a substance = C₄H₅N₂O
Further explanation
The empirical formula is the smallest comparison of atoms of compound forming elements.
A molecular formula is a formula that shows the number of atomic elements that make up a compound.
(empirical formula) n = molecular formula
((empirical formula)n=C₈H₁₀N₄O₂
divide by 2 :
(C₄H₅N₂O)₂=C₈H₁₀N₄O₂