Question

Which substance that can act as colloids as wel as crystalloids?

Answer 1

Crystalloids and colloids simply are the states of matter. Thus a same substance can act as both as colloid as well as crystalloid.

For example... a soap solution in water is an example of colloidal solution while the soap solution in water is a true solution.

Answer 2

The nature of the substance whether colloids or crystalloids depends upon size of the solute particles. While the size of solute particles lies between 1 to 1000 nm, thus it behaves as colloid