Can anyone please help me out? i’ve been stuck on this for a while

Which mathematical relationship should you us to convert moles of a substance into grams

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?

The term gas is limited to those substances that exist in the gaseous state at