To determine the oxidation state of chlorine (Cl) in [tex]\( HClO_3 \)[/tex], we can follow a systematic approach by using the known oxidation states of the other atoms in the molecule and applying the rule that the sum of oxidation states for all atoms in a neutral molecule must equal zero.
Here are the steps:
1. Identify the known oxidation states:
- Hydrogen (H) usually has an oxidation state of [tex]\( +1 \)[/tex].
- Oxygen (O) usually has an oxidation state of [tex]\( -2 \)[/tex].
2. Write the expression for the sum of the oxidation states:
For the compound [tex]\( HClO_3 \)[/tex], there is one hydrogen atom, one chlorine atom, and three oxygen atoms. Let's denote the oxidation state of chlorine as [tex]\( x \)[/tex].
3. Set up the equation:
The sum of the oxidation states must equal zero for a neutral molecule.
[tex]\[
\text{Oxidation state of } H + \text{Oxidation state of } Cl + 3 \times \text{Oxidation state of } O = 0
\][/tex]
Substituting the known values:
[tex]\[
(+1) + (x) + 3 \times (-2) = 0
\][/tex]
4. Simplify the equation:
[tex]\[
1 + x - 6 = 0
\][/tex]
5. Solve for [tex]\( x \)[/tex]:
[tex]\[
1 + x - 6 = 0 \implies x - 5 = 0 \implies x = 5
\][/tex]
6. Conclusion:
The oxidation state of chlorine (Cl) in [tex]\( HClO_3 \)[/tex] is [tex]\( +5 \)[/tex].
So, the correct answer is:
A. +5
