The empirical formula of a compound is $CH_2O$ and its molecular mass is $90$. The molecular formula of the compound is:

An organic compound contains carbon,hydrogen,and oxygen with percentages of $38.71\%$,$9.67\%$,and $51.62\%$ respectively. Determine the empirical formula of this compound.

An organic compound with $C = 40\%$ and $H = 6.7\%$ will have the empirical formula

In an analysis,the ratio of iodine to oxygen in a certain substance is $254:80$. What will be the formula of this substance? (Atomic mass $I = 127$,$O = 16$)

An organic compound contains $60\ \%\ C$, $4.48\ \%\ H$, and $35.5\ \%\ O$. Its empirical formula is:

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 $Fe = 56 \, g/mol$)