CO2 is Carbon Dioxide, true. However -- Co2 is not, if you want to get technical.
Yeah, but I don't think you'd find Co2, at least, not commonly. Cobalt Chloride comes to mind as a normal compound, but that's CoCl2. Given that cobalt in its normal state has 2 electrons in its outer shell, moving to 4 (having 2 cobolt ions together) would lend instability to the cobalt particle.
Quik, what did you edit?
Co
2 isn't what he wrote though, he wrote Co2, which could indicate Co
2, CO
2, or Co
2 , with the 2 representing a 2+ charge, and assuming that he meant Co
2+ is much more reasonable than assuming he meant Co
2. But all in all, he probably meant CO
2.