p*V = n*R*T => n = p*V/R*T => n = 1,231*2/0,082*300 = 0.1 mol hidrocarbura
n = m/masa molara => masa molara = 4.4/0.1 = 44 g/mol
%H = m H/m hidrocarbura * 100
m H = 18.18*44/100 = 8 g H
m C = m hidrocarbura - m H = 44 - 8 = 36 g C
36/12 = 3
8/1 = 8
=> FM: C3H8