Answer:
C₆H₆
Explanation:
Molar mass of the compound is 78g/mol
Unknown:
Molecular formula of the compound  = ?
Solution:
The empirical formula of the compound is CH.
Empirical formula is the simplest formula of a compound.
To solve this problem:
 Find the molar mass of CH;
    Molar mass = 12 + 1  = 13g/mol
Multiplication index  = [tex]\frac{78}{13}[/tex]   = 6
So;
       (CH)₆  ;
 Therefore:
        C₆H₆