Answer:
O2 is a covalent substance while NaCl is an ionic substance
Explanation:
In O2 molecule, the bond is between 2 oxygen atoms which are non - metals. Thus, this is a covalent bond since it involves 2 non metals.
Whereas, for the NaCl molecule, the bond is between a metal sodium (Na) and a non metal Chloride(Cl) and thus we can say this is an ionic bond.
Thus the difference is that O2 is a covalent substance while NaCl is an ionic substance.
I’m pretty sure it would be B