The percentage composition of a hydrocarbon is 79.2 carbon 20.8 hydrogen. Calculate its empirical formula [H = 1, C = 12]

A. CH
B. CH₃
C. CH₄
D. C2H2
E. C2H6

Correct Answer:

Option B – CH₃

Explanation

Relative No of Moles for Carbon = 79.2% ÷ 12 = 6.6

Relative No of Moles for Hydrogen = 20.8% ÷ 1 = 20.8

Ratio of Moles = Carbon 6.6 ÷ 6.6 = 1 Hydrogen = 20.8 ÷ 6.6 = 3

CH₃