1. Find the empirical formula mass:

* The empirical formula CH has a mass of 12.01 (C) + 1.01 (H) = 13.02 g/mol

2. Determine the ratio of molar mass to empirical formula mass:

* Molar mass / Empirical formula mass = 42.0 g/mol / 13.02 g/mol = 3.22

3. Multiply the empirical formula by the ratio:

* Since the ratio is approximately 3, multiply the subscripts in the empirical formula by 3:

* C₃H₃

Therefore, the molecular formula of the compound is C₃H₃.