Final answer:
The oxidation state of Cl in HClO4 is +7, balancing the oxidation states of H (+1) and O (-2) in the compound to make the total oxidation state equal to zero.OPTION A.
Step-by-step explanation:
To determine the oxidation state of chlorine (Cl) in perchloric acid (HClO4), we need to use the fact that the sum of all the oxidation states in a compound must equal the overall charge of the compound. In the case of HClO4, the compound is neutral, so the sum of the oxidation states must equal zero.
Oxygen (O) typically has an oxidation state of -2. Since there are four oxygen atoms in HClO4, the total oxidation state for the oxygen is -2 x 4 = -8. Hydrogen (H), when bonded to non-metals, has an oxidation state of +1. Accounting for hydrogen, we have +1 for H and -8 for the four oxygens, leaving us with +1 - 8 = -7. To balance this out and make the total oxidation state equal to zero, the chlorine atom must have an oxidation state of +7.
Therefore, the correct answer to the question is a. 7.