6. Think of NaCl, or table salt. What's the bond between NaCl? It's an ionic bond, so salts are ionic compounds. Ionic compounds refer to the electrostaticity that holds the Na atom and Cl bond together.
7. See what CO isn't first. Carbon monoxide is a gas, not a salt. And carbon monoxide is a compound, since it's made of two different elements. Since there isn't too much of electronegativity difference, CO isn't an ionic compound, so that leaves you with CO being a covalent compound.
8. If a metal + nonmetal bond, it's ionic. If it's a nonmetal + nonmetal, it's a covalent compound.
9. Ionic compounds are usually solid at room temperature-think back to NaCl like I mentioned earlier. Since there's a strong bond between the atoms in ionic compounds, it has a high melting point. Like I said earlier, ionic compounds are between metals and nonmetals. So...In ionic compounds, electrons are NOT shared. With NaCl for example, Na gives its extra electron to Cl. So it would be the third choice.
10. H2O doesn't have a metal in it, so it's not a metallic compound. H2O isn't ionic either; it's made of two nonmetals. It's also not an element, since H2O is a compound. So...if H2O is made of two nonmetals, it should be a covalent compound!
