What effect does the presence of an impurity have on the freezing point of a liquid?

When impurities are added to a liquid, the freezing point will decrease. For example, pure water at standard atmospheric pressure freezes at 0°C (32° F). If table salt (NaCl) is added to the water, the freezing point will drop to a lower temperature.

In fact, the Fahrenheit scale was developed around water fully saturated with salt. A completely salt-saturated sample of water freezes at 0° F   (-17.78 °C)

It will fall off and tip over. 

The correct answer to this question is 28