In the redox conversion of CO to CO2−

Question

3 , the oxidation number of C goes from (−2, 0, +2) to (−4, −2, +4, +6). Recall that the oxidation number of oxygen is typically −2.
1. +2; +6
2. −2; −4
3. 0; −2
4. 0; +6
5. −2; +6
6. +2; +4

Answer 1

http://www.chemteam.info/Redox/Redox-Rules.html

Answer 2

6. +2,+4