If you have 5 grams of carbon and 6 grams of hydrogen and you want to make methane, what is reaction limiting?

Methane's formula is CH4 I don't get the question but if those are the quantities of 1 of those metals, that means that you don't have enough grams of carbon. You will need 5g x 4 = 20grams of carbon.

Hope that's what you were looking for.