Chemistry help!! what one is wrong?

Question

Name=formula or formula=name. I am stuck on which one is wrong and why?

Sulfur dioxide:

SO2

Tetraphosphorus decoxide:

P4O10

H2O:

Water

N2O5:

Dinitrogen pentoxide

Ammonia:

NH3

Oxygen difluoride:

OF2

BCl3:

Boron trichloride

S2Br2:

Disulfur dibromide

chlorine:

Cl

O2:

Oxygen

dinitrogen monoxide: 

N2O

Answer 1

chlorine should be Cl2, because chlorine in its natural state is diatomic.