Question

What mass of oxygen is needed for the complete combustion of 4.60×10−3g of methane?

Answer 1

First step in answering the question is to establish a balanced chemical reaction equation. More specifically, a combustion chemical equation. 

CH4 + 2O2 ---> CO2 + 2H20

Then using dimension analysis: 

$4.60*10^{-3} g CH4 ( \frac{moleCH4}{16 g CH4}) * ( \frac{2mole O2}{mole CH4}) * ( \frac{32 g O2}{mole O2} ) = 0.0184 g O_{2}$