Final answer:
Salt water melts slower than pure water because the presence of salt lowers the freezing point of water.
Step-by-step explanation:
Salt water melts slower than pure water. When salt is dissolved in water, it lowers the freezing point of the water. This means that it takes a lower temperature for salt water to freeze compared to pure water. As a result, salt water needs to be colder than pure water in order to freeze, and therefore it takes longer for the ice to melt in salt water.