Question

A hollow glass sphere which floats with its entire volume submerged in water at 4degree Celsius , sinks when water is heated above 4 degrees Celsius . Why?

Answer 1

due to anamolus expansion of water
the sphere first sinks and then arises upward

Answer 2

Answer:

This is because at 4 degrees celcius, water is at its peak density. This high density is due to the fact that water at this temperature gets more contracted than usual and will have a low volume with a higher density.