Final answer:
The oxidation state of carbon in CO2 is +4, which balances the -4 contributed by the two oxygen atoms with an oxidation state of -2 each. Therefore, correct option is d.
Step-by-step explanation:
The oxidation state of carbon in CO2 can be determined by noting that oxygen has a generally accepted oxidation state of -2.
Because the compound CO2 is neutral, the total oxidation state of the two oxygens is -4. In order to balance this, the carbon must have an oxidation state that brings the total oxidation state of the compound to zero. This means the carbon has to have a positive oxidation number that offsets the -4 from the oxygen atoms.
The oxidation number that accomplishes this is +4, making it so the carbon's +4 and the oxygens' combined -4 cancel each other out and the molecule remains neutral.
Therefore, the answer to the question, 'Determine the oxidation state of carbon in CO2,' is +4.