The formula for calcium chlorite is

Determine the molecular formula of an oxide of iron in which the mass per cent of iron and oxygen are $69.9$ and $30.1$ respectively. Given that the molar mass of the oxide is $159.69 \, g \, mol^{-1}$.

Empirical formula of a compound is $CH_2O$ and its vapour density is $30$. The molecular formula of the compound is:

$A$ pure compound contains $2.4 \ g$ of $C$,$1.2 \times 10^{23}$ atoms of $H$,and $0.2 \ mol$ of oxygen atoms. Its empirical formula is

If we want to study the relative arrangement of atoms in a molecule,we study:

What is the percentage by mass of oxygen in $NaOH$? (Atomic mass of $Na=23 \ u, O=16 \ u, H=1 \ u$)