Question

Alum is used for making fine
clay particles in water to set-
tle down faster. explain the process​

Answer 1

Answer:

alum is usually used in colloidal solutions

Explanation:

when alum is added to the mixture, it covers the colloidal particles which are not heavy enough to settle down, but when alum covers them, they become heavy and settle down faster

Answer 2

Explanation:

After the particles are neutralized, they clump together because of something called the London Dispersion Force which are part of the Van der Waals forces. Basically, weak intermolecular force arising from quantum-induced instantaneous polarization multipoles in molecules causes even nonpolar particles to attract each other due to the correlated movements of the electrons in interacting molecules. More info can be found inside.

As to why they then settle, I think it can be sufficiently explained by gravity