What could happen if the chemists do not follow the exact formula for medications? (Give 4 or 5 examples in a sentence please and thank you)

What is the mass of sodium in 3 moles of sodium chloride

If a molecule with a molecular formula of c13h18 is treated with an excess of h2 in the presence of finally divided pt metal under conditions required for maximum hydrogenation of the molecule to give a molecule with a formula c13h24, how many rings are in the molecule?

Air can be considered a mixture. which statement does not explain why?