Which has the lowest freezing point?Select one of the options below as your answer: A. pure water B. 0.5 M ionic NaCl C. 0.5 M ionic CaCl2 D. 0.5 M ionic AlCl3 E. 0.5 M molecular C12H22O11

Answer 1

There are two ways to solve this.
1. Use delta T = i*Kf*m and calculate each of the five choices, then pick the winner.

2. Reason.
If delta T = i*Kf*m and you realize that Kf and M are the same for everything, then just look at i. m is molality and your capital M means molarity; I don't know if that's a typo but the difference is too small to worry about for this problem.
i for NaCl = 2
i for CaCl2 = 3
i for AlCl3 = 4
i for C12H22O11 = 1