What is the oxidation number of chlorine (Cl) in the compound NaClO3?

• A. +5
• B. 0
• C. +3
• D. -1

Answer: (A)

Verified step by step guidance

1. Identify the elements in the compound NaClO3: sodium (Na), chlorine (Cl), and oxygen (O).
2. Recall the common oxidation states: sodium (Na) is typically +1, and oxygen (O) is typically -2 in most compounds.
3. Set up an equation for the sum of oxidation numbers in the compound, which must equal zero because NaClO3 is neutral: let the oxidation number of chlorine be x.
4. Write the equation based on the formula NaClO3: (+1) + x + 3(-2) = 0.
5. Solve the equation for x: +1 + x - 6 = 0, which simplifies to x - 5 = 0, so x = +5. This means the oxidation number of chlorine in NaClO3 is +5.