An organic compound is estimated through the Dumas method and is found to evolve $6$ moles of $CO_2$,$4$ moles of $H_2O$,and $1$ mole of nitrogen gas. The formula of the compound is

Chlorophyll, the green pigment in plants responsible for photosynthesis, contains $2.68\%$ of magnesium by mass. Calculate the number of magnesium atoms in $2.00 \ g$ of chlorophyll.

$A$ 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

$64 \, g$ of an organic compound contains $24 \, g$ of carbon,$8 \, g$ of hydrogen,and the rest oxygen. The empirical formula of the compound is

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 $162\, g\, mol^{-1}$.

The empirical formula of Calgon is