Answer:
Step-by-step explanation:
CO2 is a covalent bonding. It is something from the middle of the periodic table bonded with something on the right of the periodic table. It is not ionic.
NH3 is also covalent. The H bonds with the N and the H has properties that resemble both the metals and non metals. That's why it is on both the left and right sides of the periodic table. In this case, it is more non metallic than metallic. Since Nitrogen is on the right side of the table, you have a situation where 2 nonmetals are bonding. It is not ionic.
The answer is NaF. Sodium is on the left side of the periodic table and F is on the right side. That's what it takes to get an ionic bond.