Question

Making settling of finer particles faster with alum

Answer 1

Answer:

   The particles are all similar and ionized, so therefore they have a similar charge (positive, I think) causing them repel each other and stay separate.

   And because they're so small, the gravitational force acting on them isn't very strong either.

   Also, the dust particles, previously dispersed in the air, have a lot of kinetic energy already.

Explanation: