Общая формула алканов CnH2n+2
a) C6H14 - гексан
M(C6H14) = 86 g/mol
W(C) = 12*6 / 86 = 0.837
W(H) = 1*14 / 86 = 0.163
b) C5H12 - Пентан
M(C5H12) = 72 g/mol
W(C) = 12*5 / 72 = 0.833
W(H) = 12*1 / 72 = 0.167
c) C3H8 - Пропан
M(C3H8) = 44 g/mol
W(C) = 12*3 / 44 = 0.818
W(H) = 8*1 / 44 = 0.092