calculez masa molara a compusului din densitatea realtiva
d=M./M,aer---> M= 3,9X 29g/mol= 113g/mol
100g compus......31,9g C......5,3gH......62,89gCl
113g........................x..............y................z
x=36gC.........n,C= 36g/12g/mol= 3
y=6gH...........n,H= 6
Z= 71gCl------n,Cl= 71g/35,5g/mol= 2
compusul este C3H6Cl2-dicloropropan