A hydrocarbon X with a molar mass of 26 consists of 92.3% carbon. What is its molecular formular?

A. C2H2
B. C3H3
C. C4H4
D. C5H5

Correct Answer:

Option A – C2H2

Explanation

% of H2 = 100 – 92.3 = 7.7%
mole = 92.3/12; ⇔ 7.7/1
7.1/7.1; ⇔ 7.1/7.1

empirical formula = CH
(CH)n = 26
(12 + 1)n = 26
(13)n = 26
n = 26/13 = 2
molecular formula = C2H2