$A$ compound contains $2.2 \ g$ of phosphorus and $1.24 \ g$ of sulfur. What is its empirical formula?

An organic compound containing $C$,$H$,and $N$ gave the following analysis: $C = 40\%$,$H = 13.33\%$,and $N = 46.67\%$. Its empirical formula would be:

If the weight percentage of $Se$ (at. wt. $78.4$) in peroxidase anhydrous enzyme is $0.5 \%$,what is the minimum molecular weight of the enzyme?

$1.25 \ g$ of a metal $(M)$ reacts with oxygen completely to produce $1.68 \ g$ of metal oxide. The empirical formula of the metal oxide is
[molar mass of $M$ and $O$ are $69.7 \ g \ mol^{-1}$ and $16.0 \ g \ mol^{-1}$,respectively]

$25 \ g$ of an unknown hydrocarbon upon burning produces $88 \ g$ of $CO_2$ and $9 \ g$ of $H_2O$. This unknown hydrocarbon contains:

What is the percentage of nitrogen in urea (in $\%$)?