Final answer:
In COCl₂, carbon (C) has an oxidation number of +4, oxygen (O) has an oxidation number of -2, and each chlorine (Cl) has an oxidation number of -1, ensuring that the total oxidation numbers balance out to zero, as the compound is neutral.
Step-by-step explanation:
The oxidation number of each type of atom in COCl₂ is determined by using a set of rules. For oxygen (O), the commonly assigned oxidation number is -2 by rule 3. In COCl₂, there are two Cl atoms; chlorine (Cl) typically has an oxidation number of -1 when it is part of a compound as it is usually more electronegative than other atoms it is bonded to, except for oxygen. Since the compound is neutral, the sum of the oxidation numbers must equal zero. Given that we have two Cl atoms, their combined oxidation number would be -2 (-1 for each). The one oxygen atom would have an oxidation number of -2. Therefore, the carbon (C) atom must have an oxidation number that balances the total to zero. To do this, the carbon would have an oxidation number of +4.
The complete breakdown is: C: +4, O: -2 (for one oxygen), and Cl: -1 (for each chlorine atom). Therefore, the oxidation numbers for COCl₂ are +4 for C, -2 for O, and -1 for each Cl atom.