The sixth member of the class of the aliphatic alkanes is Hexane with the molecular formular C\(_6\)H\(_{14}\)

Percentage by mass of Hydrogen =  \(\frac{mass of Hydrogen in compound}{Total mass of compound}\)\(\times 100\)

Total mass of compound, C\(_6\)H\(_{14}\) = (12 x 6) + (1 x14) = 72 + 14 = 86

Mass of Hydrogen in compound = 14(H) = 14\(\times 1\) = 14

% mass of H = \(\frac{14}{86}\)\(\times 100\)

 = 16.28%