Answer is: empirical formula is H₄N₂O₂.
m(unknown compound) = 8,5 g.
m(N₂) = 2,37 g.m(H₂O) = 3,04 g.
n(N₂) = m(N₂) ÷ M(N₂).
n(N₂) = 2,37 g ÷ 28 g/mol.
n(N₂) = 0,0846 mol.
n(H₂O) = m(H₂O) ÷ M(H₂O).
n(H₂O) = 3,04 g ÷ 18 g/mol.
n(H₂O) = 0,168 mol.
n(H₂O) : n(N₂) = 0,168 mol : 0,0846 mol.
n(H₂O) : n(N₂) = 2 : 1.
Compound has four hydrogen, two oxygen and two oxygen.