Final answer:
The oxidation state of Cl in HClO₄ is +7, in order to balance the oxidation states of the other elements in the compound and achieve a neutral overall charge.Correct answer is option d.
Step-by-step explanation:
The oxidation state of Cl in HClO₄ can be determined by considering the oxidation states of the other atoms and the overall charge of the compound. In HClO₄, hydrogen (H) has an oxidation state of +1, and oxygen (O) has a typical oxidation state of -2. Since there are four oxygen atoms, their total contribution is -8.
The compound is neutral, so the sum of the oxidation states must be zero. Therefore, to balance the 1+ from hydrogen and the 8- from the oxygen atoms, chlorine (Cl) must have an oxidation state of +7.