Question

balance the following equation: ?h₂ + o₂ → h₂o
remember: the number of atoms for each element should be equal on the reactant and product sides.
2
1
4
3

Explanation:

Step1: Balance oxygen atoms

On the left - hand side, oxygen is in $O_2$, and on the right - hand side in $H_2O$. To balance oxygen, we need 2 moles of $H_2O$ for 1 mole of $O_2$ since there are 2 oxygen atoms in $O_2$ and 1 oxygen atom in $H_2O$. So the equation becomes $H_2+O_2
ightarrow2H_2O$.

Step2: Balance hydrogen atoms

Now, on the right - hand side, we have 4 hydrogen atoms in $2H_2O$. So we need 2 moles of $H_2$ on the left - hand side to balance the hydrogen atoms. The balanced equation is $2H_2 + O_2
ightarrow2H_2O$.

Answer:

2, 1, 2