A molecular formula represents the exact number of atoms present for each element in the compound.
For carbon atom: [tex]\frac{78}{12}[/tex] = [tex]6\frac{6}{12}[/tex] ( as molar mass of carbon is 12 g/mol)
Now, 6 carbon atoms are present and rest are hydrogen atoms i.e. 6
Thus, formula becomes [tex]C_{6}H_{6}[/tex] ( [tex]C_{x}H_{y})[/tex]
Now, check for unsaturation:
Degree of unsaturation = [tex]\frac{2x+2-y}{2}[/tex]
Substitute the value of x and y,
Degree of unsaturation = [tex]\frac{2(6)+2-6}{2}[/tex]
= [tex]\frac{12-4}{2}[/tex]
= [tex]4[/tex] implies one ring and three double bonds.
Thus, formula comes out to be [tex]C_{6}H_{6}[/tex] i.e. benzene ring.
