Question

water expand on reducing it's temperature below at what degree Celsius

Answer 1

4 degrees C turns out to be the temperature at which liquid water has the highest density. If you heat it or cool it, it will expand. The expansion of water when you cool it to lower temperatures is unusual, since most liquids contract when they're cooled.

Answer 2

Water often contracts between 0 to 4 degree Celsius than if we reduce the temperature below 0 Degree Celsius than it will expaned