Percentage composition of hydrogen in benzene C6H6 is

SOLUTION

Molecular mass of benzene is $=(12\times 6)+(6\times 1)=78u$

Mass percentage of an element= $\frac{\text{Mass of an element}}{\text{Mass of compound}}\times 100$ = $\frac{6}{78}$ $\times 100$$=7.7\%$