Salt water freezes at approximately what temperature?

• A. -2°C
• B. 0°C
• C. 2°C
• D. -4°C

Answer: (A)

Salt in water lowers the temperature at which it freezes. This is freezing point depression: dissolved salts disrupt ice crystal formation, so seawater freezes at a lower temperature than pure water.

For typical seawater, about 3.5% salinity, the freezing point is around -2°C. The exact value varies with how salty the water is, but -2°C is the common approximation students memorize.

So, -2°C is the best answer because it reflects the depressed freezing point of salt water, unlike pure water (0°C) or much colder possibilities that aren’t representative of normal seawater.