Which of the following chemical equations is NOT balanced?

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

Answer: (C)

Verified step by step guidance

1. Step 1: Understand what it means for a chemical equation to be balanced. A balanced equation has the same number of atoms of each element on both the reactant and product sides.
2. Step 2: Check the first equation: \$2\ KClO_3 \rightarrow 2\ KCl + 3\ O_2$. Count atoms on both sides: Potassium (K), Chlorine (Cl), and Oxygen (O). Confirm that the number of atoms for each element is equal on both sides.
3. Step 3: Check the second equation: \$2\ H_2 + O_2 \rightarrow 2\ H_2O$. Count Hydrogen (H) and Oxygen (O) atoms on both sides to verify balance.
4. Step 4: Check the third equation: \(Na + Cl_2 \rightarrow 2\ NaCl\). Count Sodium (Na) and Chlorine (Cl) atoms on both sides. Notice if the number of atoms matches or not.
5. Step 5: Check the fourth equation: \(C_3H_8 + 5\ O_2 \rightarrow 3\ CO_2 + 4\ H_2O\). Count Carbon (C), Hydrogen (H), and Oxygen (O) atoms on both sides to confirm if the equation is balanced.