[Physics] Why water behaves strangely at 4 degree celsius

phase diagramphase-transitiontemperaturethermodynamicswater

The basic physics concept I hope almost every one might be aware of i.e "water tend to expand instead of freezing just below and above 4 degree celsius".
My question is why exactly at 4 degrees this phenomenon occur? Why not at some other temperature also what makes it to behave that way?.

Any explanation for the reason might be greatly appreciated.

Best Answer

sou said, "water tend to expand instead of freezing just below and above 4 degree celsius".

Take a look at a chart Wikipedia.

https://en.wikipedia.org/wiki/Properties_of_water#/media/File:Density_of_ice_and_water_(en).svg

This shows that the expansion of liquid water takes place between 0 and 4 degrees C, and that when ice is formed from liquid water at exactly 0 degrees C, it expands.