We have three knowns grams because remember, grams will translate into moles. We can find moles using grams. So our first step will be to find our third unknown. To find our number of moles. If we find that we have three knowns and one unknown, we'll suffer that unknown, namely this guy, and we'll get our answer. So to find the number of moles n, we simply take our number 0.5
grams of methane.