How much would the freezing point of water decrease if 4 mol of nacl were added to 1 kg of water (kf = 1.86°c/(mol/kg) for water and i = 2 for nacl)?

a. 14.88°c
b. 3.72°c
c. 7.44°c
d. 1.86°c

answer asap

Freezing point decrease is a colligative property.

Freezing point decrease is given by the formula:

ΔfT = Kf * i * m

m = # moles solute / Kg solvent

# moles solute = 4 mol

Kg solvent = 1 Kg

=> m = 4 mole / 1 Kg = 4m

=> ΔTf = 1.86 °C / m * 2 * 4 m =  14.88 °C

14.88°C

Neither model is able to show the reactivity of potassium.