Covalent
Reason
As the combining atoms i.e., S and O are non-metals and they both have high electron affinity hence they share two pairs of valence electrons in order to complete their octet and attain a stable state and hence form covalent bond.
Covalent
Reason
As the combining atoms i.e., S and O are non-metals and they both have high electron affinity hence they share two pairs of valence electrons in order to complete their octet and attain a stable state and hence form covalent bond.