Given a scientific passage and an answer, generate a question for the given answer.
Q: Passage: A: If calcium chloride dissolves in water, it breaks down into its ions (Ca 2+ and Cl - ). When water has ions dissolved in it, it has a lower freezing point. Pure water freezes at 0C. With calcium and chloride ions dissolved in it, it won't freeze unless the temperature reaches -29C or lower. Answer: zero degrees
A:
In celsius, what is the temperature at which water freezes?