The empirical formula of Calgon is

If a compound contains $C = 18.5\%$,$H = 1.55\%$,$Cl = 55.04\%$,and $O = 24.81\%$,then its empirical formula is .....

The molecular mass of caffeine is $194 \, a.m.u.$. It contains $28.9 \%$ of nitrogen by mass. The number of nitrogen atoms in one molecule of caffeine is ...............

The empirical formula of a compound is $C_2H_5O$ and its vapour density is $45$. What is the molecular formula of the compound?

Compound $A$ contains $8.7\,\%$ Hydrogen,$74\,\%$ Carbon and $17.3\,\%$ Nitrogen. The molecular formula of the compound is ....
Given : Atomic masses of $C$,$H$ and $N$ are $12$,$1$ and $14\, amu$ respectively.
The molar mass of the compound $A$ is $162\, g\, mol^{-1}$.

$0.102 \ g$ of an organic compound $X$ was oxidised with fuming nitric acid. The resulting solution,after reaction with excess of aqueous $BaCl_2$,produced $0.233 \ g$ of $BaSO_4$ as a precipitate. Compound $X$ is likely to be: [Given: Atomic wt. of $Ba = 137$]