Experiments about Egg Buoyancy 

If we put an egg in water, it sinks because its density is bigger than that aof water.
If we add some solute like sugar or salt, the density of the solution will increase so the egg will float.
If we heat the water (salt water) the volume will increase and so the density will decrease so the will sink again. When the water gets cold the egg will float again.
en.wikipedia.org/wiki/Egg
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en.wikipedia.org/wiki/Buoyancy
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