An ionic bond is a type of chemical bond formed through an electrostatic attraction between two oppositely charged ions. Ionic bonds are formed between a cation, which is usually a metal, and an anion, which is usually a nonmetal. A covalent bond involves a pair of electrons being shared between atoms.
Molecular Weight (MW) is the sum of the atomic weights/masses (AM) of every atom in a compound or molecule. Thus, we would add the AM of Mg + 2×[N+(O×3)]:
Mg = 24.31
N = 14.01
O = 16
So we have: Mg + 2×[N+(O×3)] = 24.31 + 2×[14.01+(16×3)] = 24.31+2×[14.01+48] = 24.31+ 2×62.01 = 24.31+124.02 = 148.33
C) is the correct answer
