Column A:
1. The oxidation number of Oxygen (O) in Cs2O is e. 0.
2. The oxidation number of Oxygen (O) in O2 is e. 0.
3. The oxidation number of Calcium (Ca) in CaI2 is d. +2.
4. The oxidation number of Fluorine (F) in SnF2 is b. -2.
5. The oxidation number of Titanium (Ti) in TiO2 is a. +4.