Determine the molecular weight for mg (no3) 2.

134.32 g

118.32 g

148.33 g

172.64 g

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