To balance the chemical equation, we need to ensure that the number of atoms for each element is the same on both sides of the equation.H2 + O2 -> H2OFirst, we notice that there are 2 hydrogen atoms on the left side of the equation and only 2 hydrogen atoms on the right side. However, there are 2 oxygen atoms on the left side and only 1 oxygen atom on the right side. To balance the equation, we can adjust the coefficients:2H2 + O2 -> 2H2ONow, the equation is balanced with 4 hydrogen atoms and 2 oxygen atoms on both sides.Reactants: H2 hydrogen gas and O2 oxygen gas Products: H2O water