Answer :
Covalent compound : It is defined as the compound which is formed by the sharing of electrons between the atoms forming a compound.
The covalent compound are usually formed when two non-metals react.
Ionic compound : It is defined as the compound which is formed when electron gets transferred from one atom to another atom.
All the polyatomic ions always form an ionic compound.
Polyatomic ions : It is a charged species that composed of two or more atoms and these charged species are bonded by the covalent bond.
For the given options:
Option A:
This compound is formed by the combination of potassium, which is a metal and
ion which is a polyatomic ion. Thus, it will form an ionic compound.
Option B:
This compound is formed by the combination of magnesium, which is a metal and
ion which is a polyatomic ion. Thus, it will form an ionic compound.
Option C:
Hydrogen and sulfur, both are non-metals and they will form a covalent compound.
Option D:
This compound is formed by the combination of silver, which is a metal and sulfur,
which is a non-metal. Thus, it will form an ionic compound.
Option E:
Nitrogen and chlorine, both are non-metals and they will form a covalent compound.
Option F:
This compound is formed by the combination of cobalt, which is a metal and
ion which is a polyatomic ion. Thus, it will form an ionic compound.