What is the freezing point of a solution of 7.15 g MgCl₂ (an electrolyte) in 100 g of water? Some possibly useful constants for water are Kf = 1.86 °C/m and Kb = 0.512 °C/m.
A) -0.140 °C
B) -4.18 °C
C) 4.18 °C
D) -1.40
E) -2.80 °C.