In which one of the following molecules does chlorine have the highest oxidation number?

• A. ClO2
• B. ClO3^-
• C. Cl2
• D. ClO4^-

Answer: (D)

Verified step by step guidance

1. Recall that the oxidation number of chlorine in a compound depends on the overall charge of the molecule or ion and the known oxidation states of the other atoms involved.
2. Assign the oxidation number of oxygen as -2 (a common oxidation state for oxygen in most compounds except peroxides and superoxides).
3. Set up an equation for the sum of oxidation numbers in each species, remembering that the sum must equal the overall charge of the molecule or ion.
4. For example, in ClO2, let the oxidation number of Cl be x. Since there are two oxygens each with -2, the equation is: \(x + 2(-2) = 0\).
5. Repeat this process for ClO3^-, Cl2, and ClO4^- (even though ClO4^- is not listed in the options, it is given as the correct answer), and compare the values of x to determine which molecule has the highest oxidation number for chlorine.