The oxidation number of iodine in KIO3 is

Analysis

To find the oxidation number of iodine (I) in potassium iodate ($KIO_3$), we use the rules of oxidation states. The sum of the oxidation numbers of all atoms in a neutral compound must equal zero.

Concept

• Potassium (K): As a Group 1 element, it always has an oxidation number of +1.
• Oxygen (O): In most compounds (like this one), it has an oxidation number of -2.
• Iodine (I): This is the unknown element we need to solve for. Let's represent it as $x$.

Step-by-Step Solution

1. Set up the equation: The sum of the oxidation numbers in $KIO_3$ is: $(K) + (I) + 3(O) = 0$

2. Substitute the known values: $(+1) + (x) + 3(-2) = 0$

3. Simplify the equation: $1 + x - 6 = 0$ $x - 5 = 0$

4. Solve for $x$: $x = +5$

The oxidation number of iodine in $KIO_3$ is +5.

Conclusion

Comparing our result with the given options: A. +7 B. +3 C. +5 D. +6

The correct option is C.

Exam Tip

When calculating oxidation numbers, always remember that the sum of oxidation states for a neutral molecule is 0, but if you are dealing with a polyatomic ion (like $SO_4^{2-}$), the sum must equal the charge of the ion (in this case, -2). This is a common trap in JAMB Chemistry!