Question

in the reaction of methane combustion, the balanced equation produces two molecules of carbon dioxide and two molecules of

Explanation:

Step1: Recall methane combustion reaction

Methane ($CH_4$) burns in oxygen ($O_2$) to produce carbon - dioxide ($CO_2$) and water ($H_2O$). The general un - balanced equation is $CH_4 + O_2
ightarrow CO_2+H_2O$.

Step2: Balance the equation

For the given situation where 2 moles of $CO_2$ are produced, since there is 1 carbon atom in $CH_4$, we need 2 moles of $CH_4$. Then, for hydrogen, 2 moles of $CH_4$ have 8 moles of hydrogen atoms. So, we get 4 moles of $H_2O$ to balance hydrogen. And for oxygen, 2 moles of $CO_2$ have 4 moles of oxygen atoms and 4 moles of $H_2O$ have 4 moles of oxygen atoms, so we need 4 moles of $O_2$. The balanced equation is $2CH_4 + 4O_2
ightarrow2CO_2 + 4H_2O$.

Answer:

Water