What is the percentage of carbon in urea (in $\%$)? $(At. mass C = 12, H = 1, N = 14, O = 16)$

If $0.0833 \, \text{mol}$ of a carbohydrate contains $1 \, \text{g}$ of hydrogen and its empirical formula is $CH_2O$,what is its molecular formula?

Hemoglobin contains $0.334 \% \, Fe$ by weight. If the molecular mass of hemoglobin is approximately $67200 \, g/mol$,determine the number of iron atoms in one molecule of hemoglobin. (Atomic mass of $Fe = 56 \, g/mol$)

Find the empirical formula of an organic compound if it contains $18.6 \% C$,$1.55 \% H$,and $55.04 \% Cl$. (Atomic masses: $C=12$,$H=1$,$Cl=35.5$,$O=16$)

$0.5 \ g$ of an organic compound $(X)$ with $60 \%$ carbon will produce $........ \times 10^{-1} \ g$ of $CO_2$ on complete combustion.

In an $80 \, g$ compound,the masses of elements are $C = 24 \, g$,$H = 4 \, g$,and $O = 32 \, g$. Find its empirical formula.