In this reaction, what is the correct coefficient for hydrogen gas? \( ? \mathrm{H}_{2}+? \mathrm{O}_{2} \rightarrow ? \mathrm{H}_{2} \mathrm{O} \) 2

To balance the reaction \( ? \mathrm{H}_{2}+? \mathrm{O}_{2} \rightarrow ? \mathrm{H}_{2} \mathrm{O} \), you'll need to ensure that the number of atoms of each element is the same on both sides. Since each water molecule (H₂O) contains two hydrogen atoms, you would need two molecules of hydrogen gas (H₂) for every molecule of water produced. Thus, the correct coefficient for hydrogen gas is 2. When balancing chemical equations, it's important to make a systematic approach. Start by balancing the atoms of elements present in compounds, then move on to individual elements like H and O. Keep track of the coefficients while ensuring that they remain whole numbers. Balancing requires practice, so don't hesitate to double-check your results or try different combinations!