# Question #0b108

Well, there are $20 \cdot m o l$ of hydrogen, so approx. $20 \cdot g$........
In one mole of methane we have a mass $16.0 \cdot g$. Carbon constitutes $12 \cdot g$ of this mass, and $4 \cdot g$ of this are hydrogen. If there is a $5.0 \cdot m o l$ quantity of methane, clearly there are $4 \times 5 \cdot m o l$ hydrogen, and a mass with respect to hydrogen of approx. $20 \cdot g$. What is the mass of carbon in this quantity?