Question

what do you understand by anomolous expanssion of water ?

Answer 1

the phenomena of water expansion at 4°Celsius is called anolmolous expansion of water

Answer 2

The anomalous expansion of water is an abnormal property of water whereby it expands instead of contracting when the temperature goes from 4oC to 0oC, and it becomes less dense. The density becomes less and less as it freezes because molecules of water normally form open crystal structures when in solid form.