Covalent compounds share with each other, whilst Ionic compounds take from each other.
Covalent compounds are composed of 2 or more NONMETALS.
So, it would be CO, since the rest of the compounds contain metals in them.
The options ? We can’t answer your questions without any options or choices
<span>There is a direct correlation between the period number and the energy level for valence electrons. For example, the H and He elements, in period 1, have their outer electrons in the energy level "1". This continues down the rows: all the elements in period 2 have their principal energy level as n = 2, period 3 has n = 3, and so on.</span>