Which of the following chemical equations is unbalanced?

• A. 2 H_2 + O_2 ightarrow 2 H_2O
• B. Na + Cl_2 ightarrow 2 NaCl
• C. C_3H_8 + 5 O_2 ightarrow 3 CO_2 + 4 H_2O
• D. 2 KClO_3 ightarrow 2 KCl + 3 O_2

Answer: (B)

Verified step by step guidance

1. Identify the chemical species on both sides of each equation and count the number of atoms of each element in the reactants and products.
2. For the first equation: \$2\ H_2 + O_2 \rightarrow 2\ H_2O$, count hydrogen and oxygen atoms on both sides to check if they are equal.
3. For the second equation: \(Na + Cl_2 \rightarrow 2\ NaCl\), count sodium and chlorine atoms on both sides to verify if the equation is balanced.
4. For the third equation: \(C_3H_8 + 5\ O_2 \rightarrow 3\ CO_2 + 4\ H_2O\), count carbon, hydrogen, and oxygen atoms on both sides to confirm balance.
5. For the fourth equation: \$2\ KClO_3 \rightarrow 2\ KCl + 3\ O_2$, count potassium, chlorine, and oxygen atoms on both sides to ensure the equation is balanced.