Why does a lump of cotton wool shrink in water? This is a physical or a chemical change?

Lump of cotton is solid but it has space or air gaps of cotton fibers.

When it is put in the water the water molecules take the place of these gaps making the lump heavy and shrink as the air gaps are removed.

Since there is no change in the chemical property, it is a physical change.

Cotton wool shrinks in water as it has air gaps which get replaced by water when put in the water making it shrink.

This is a physical change.