Question

We all have observed that ice floats on liquid water. Why? What is unusual about this?

Answer 1

Why? You have got a solid phase, that is LESS DENSE than its liquids phase.....

Explanation:

And normally, we would expect that solid phase, which is arguably the most ordered phase, would be DENSER than the liquid phase. And water is a HIGHLY unusual material in that `rho_"ice"` `<` `rho_"water"`.

And what is the result? Well, icebergs float...for most other liquids the solid phase is MORE dense than the liquid phase, and would SINK.

So next time you see the film `"Titanic"`, the 1950's film with Clifton Webb, still brings tears to my eyes, no matter how cynical I try to be...think about that....