The empirical formula of compound is ${\mathrm{CH}}_2\mathrm{O}$ .Its molecular weight is 90. The molecular formula of compound is ____?

$\mathrm{Molecular} \mathrm{weight} = \mathrm{n}\times \mathrm{empirical} \mathrm{weight} (\mathrm{n}=\mathrm{whole} \mathrm{number})$

Empirical weight is calculated as:

$\mathrm{Empirical} \mathrm{molecular} \mathrm{weight}=12+2\left(1\right)+16=30$

Value of n is calculated as:

$$\begin{gathered} 90=\mathrm{n}\times 30 \\ \mathrm{n}=\frac{90}{30}=3 \end{gathered}$$

Molecular Formula will be ${\left({\mathrm{CH}}_2\mathrm{O}\right)}_3$.