Explanation:
When there is transfer of electrons between two atoms then it results in the formation of an ionic bond.
Whereas when there is sharing of electrons between two atoms then it results in the formation of covalent bond.
, , and are ionic compounds as there is bond formation between a metal and a non-metal. So, there will be transfer of electrons and as a result, ionic bond is formed.
is a compound which contains non-metals C and S. Therefore, bond formation is due to sharing of electrons thus, there is covalent bond.
has symmetrical structure and will have equal sharing of electrons. Hence, the molecule will have non-polar covalent bond.