Which of the following chemical equations is balanced correctly?

• A. H_2 + 2 O_2 ightarrow 2 H_2O
• B. 2 H_2 + O_2 ightarrow 2 H_2O
• C. H_2 + O_2 ightarrow H_2O
• D. 2 H_2 + 2 O_2 ightarrow 2 H_2O

Answer: (B)

Verified step by step guidance

1. Identify the chemical species involved in the reaction: hydrogen gas (\(H_2\)) and oxygen gas (\(O_2\)) react to form water (\(H_2O\)).
2. Write the general form of the reaction: \(a\,H_2 + b\,O_2 \rightarrow c\,H_2O\), where \(a\), \(b\), and \(c\) are coefficients to be determined.
3. Balance the hydrogen atoms first by ensuring the number of hydrogen atoms on the reactant side equals the number on the product side. Since each \(H_2\) molecule has 2 hydrogen atoms and each \(H_2O\) molecule has 2 hydrogen atoms, set \$2a = 2c\( which simplifies to \)a = c$.
4. Balance the oxygen atoms next by ensuring the number of oxygen atoms on the reactant side equals the number on the product side. Each \(O_2\) molecule has 2 oxygen atoms and each \(H_2O\) molecule has 1 oxygen atom, so set \$2b = c$.
5. Use the relationships from steps 3 and 4 to find the smallest whole number coefficients \(a\), \(b\), and \(c\) that balance the equation, then compare these coefficients to the options given to identify the correctly balanced equation.