Insulin contains $3.4 \%$ sulfur by weight. What is its minimum molecular mass?

The empirical formula of Calgon is

$A$ compound contains $2.34 \ g$ of nitrogen and $5.34 \ g$ of oxygen. What is the empirical formula of the compound?

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 $159.69 \, g \, mol^{-1}$.

$A$ hydrocarbon contains $80\%$ carbon and its vapor density is $15$. What is the hydrocarbon?

Calculate the mass percentage of different elements present in sodium sulfate $(Na_2SO_4)$.