Give scientific reasons : In very cold regions, water pipes sometimes burst in winter.

Answer: Because water expands when it is cooled below 4 °C and on freezing, due to its anomalous behaviour.

• Most liquids contract on cooling, but water contracts only down to 4 °C. When it is cooled from 4 °C to 0 °C it expands, and when it freezes into ice its volume increases further.
• In winter the water inside the pipes freezes. The ice occupies more volume than the water, so it exerts a large pressure on the walls of the pipe.
• This pressure makes the pipes crack or burst.