J.R. S. answered 04/04/19
Ph.D. University Professor with 10+ years Tutoring Experience
∆T = imK
∆T = change in freezing point = ?
i = van't Hoff factor = 2 for NaCl (Na+ and Cl-)
m = molality = 0.1
K = freezing point constatn = 1.86
∆T = (2)(0.1)(1.86) = 0.372 degrees
New freezing point will be -0.372 degrees C since normal freezing point is 0ºC