A Solution Is Made by Dissolving 1

A solution is made by dissolving 1.25 moles of magnesium nitrate in 300.0 g of water. If the van't Hoff factor, i, for this particular concentration is 2.25, what is the expected freezing point of this solution? K_f = 1.86 °C m^-1.

A) -0.45°C
B) -1.57°C
C) -3.44°C
D) -5.23°C
E) -17.4°C