1. Au is single element (gold)
Hg-single
H2O compound (H is on element O is another)
C is single
CO compound (C is one and O is another)
MgCl2 compound (Mg is one single and Cl is another single)
Co is single
Mn is single
HCl compound (H is single and Cl is single)
HSO are all single elements in a compound
