Dental Admissions Test (DAT) Practice Test

What happens to the melting point as the molality of a solution increases?

1. a. Increases

2. b. Decreases

3. c. Remains constant

4. d. Becomes unpredictable

The correct answer is: b. Decreases

As the molality of a solution increases, the melting point decreases. This is because adding solutes to a solvent creates a colligative effect, reducing the overall freezing point of the solution. In other words, the presence of solutes disrupts the orderly arrangement of solvent molecules, making it more difficult for the solution to freeze and lowering the temperature at which this occurs. Therefore, A is incorrect as the melting point does not increase with increasing molality. C is also incorrect as the melting point does not remain constant. D is incorrect as the effect of increasing molality on the melting point can be predicted and is not unpredictable.