Answer:148.31 Grams per mol
Explanation: It has been a long time since I took chemistry.
I believe you add up all the elements molar mass.
magnesium nitrate is Mg(NO3)2 so you add
MG 24.30
N 14.01 * 2 = 28.01
O 16.00 * 6 = 96.00
total is 148.31 grams per mol
I hope this helps.