The empirical formula of compound is CH. Its molecular mass is 78. The compound is

The empirical formula of compound is CH. The mass of empirical formula of compound is 

12 +1 =13

The molecular mass of the compound is 78.

Therefore, the number of mole of the compound =$\frac{\mathrm{molecular} \mathrm{mass}}{\mathrm{Empirical} \mathrm{formula} \mathrm{mass}}$

$=\frac{78}{13}=6$

Therefore, the compound is ${\left(\mathrm{CH}\right)}_{6}or C_6{H}_6 or benzene$