If a solution were to change its composition during freezing, how do you think this would change the cooling curve?

freezing point increases.

Explanation:

NB:kindly check attached file/picture for the diagram showing COOLING CURVE.

A cooling curve is a plot of temperature against time. It represents the change of phase of matter either from a gas to a solid or a liquid to a solid. The "cooling rate" is the slope of the cooling curve at any point.

The starting temperature, labelled A from the diagram is the POURING TEMPERATURE, the labelled B is the EQUILIBRIUM TEMPERATURE.

IF A SOLUTION were to CHANGE its composition during freezing, the Freezing Point will increase because as the solution gets more colder, some solute would drop out of solution. As solute drop out of the solution it will cause an increament in the freezing point.

your answer would be a. 12.5 kg