Step 1: We can start solving this problem using the molecular mass of CH2.
For CH2
C =12.011 g/mole
+ H = 1.008 g/mol x 2
-------------------------
14.027 g/mole
Step 2. Get the ratio of the empirical mass and the molecular mass.
= 56.1/14.027
= 3.999 = 4
Step 3. Multiply the resulting number with the subscripts of the empirical formula.
4(CH2) = C4H8
The molecular formula is C4H8.