ANSWER
8 moles of water
EXPLANATION
The major products formed when an organic compound undergo combustion reaction are water and carbon dioxide
Below is the combustion formula
[tex]\text{ C}_xH_y\text{ + x + }\frac{y}{4}O_2\text{ }\rightarrow\text{ xCO}_2\text{ + }\frac{y}{2}H_2O[/tex]In the question above, 4 moles of methane reacts with oxygen
[tex]\begin{gathered} \text{ 4CH}_4\text{ + 4+}\frac{16}{4}O_2\text{ }\rightarrow\text{ 4CO}_2\text{ + }\frac{16}{2}H_2O \\ \\ \text{ 4CH}_{4(g)}\text{ + 8O}_{2(g)}\text{ }\rightarrow\text{ 4CO}_{2(g)}\text{ + 8H}_2O(l) \end{gathered}[/tex]Therefore, 4 moles of methane will give 8 moles of water
