An oxide of iron,which contains $69.9 \%$ iron and $30.1 \%$ dioxygen by mass,has the empirical formula:

Which of the following substances has the same empirical formula as glucose?

On combustion,$0.210 \ g$ of an organic compound containing $C$,$H$,and $O$ gave $0.127 \ g$ $H_2O$ and $0.307 \ g$ $CO_2$. The percentages of hydrogen and oxygen in the given organic compound respectively are $:$

An organic compound with a molecular weight of $60$ contains $C = 20\%$,$H = 6.67\%$,and $N = 46.67\%$,with the remainder being oxygen. Upon heating,the solid residue gives a violet color with alkaline copper sulfate solution. Identify the compound.

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

If two compounds have the same empirical formula but different molecular formulae,they must have: