Question

2CO + 2NO yields 2CO2 + N2
In this redox reaction, how do I know whether the carbon becomes a +4 charge while the Oxygen stays at -2, or whether the carbon remains the same while the oxygen changes to -1?

Answer 1

Oxygen is -2 except in peroxides, where it is -1. That does not apply here, so oxygen remains at -2. That will enable you to figure out how to assign the other oxidation numbers.