Determination of molecular formulas

Exercise 5

    

A monocyclic organic substance has an alcohol function. The percentage of oxygen is $12.5\; \%$. Find its molecular formula.

General molecular formula: $C_nH_{2n}O$ $\frac{16}{12n+2n+ 16}$ $ =$ $ 0.125$ $n$ $=$ $8$ $C_8H_{16}O$