Answer
a) Covalent
b) Ionic
c) Ionic
d) Covalent
Work Step by Step
a) It is covalent because the difference in electronegativity is less than 1.8
b) It is ionic because the difference in electronegativity is more than 1.8
c) It is ionic because the difference in electronegativity is more than 1.8
d) It is covalent because the difference in electronegativity is less than 1.8