Science! Filtration?

Question

Thanks for helping me!
Filtration:
Q1 What property does filtration depend on?
Q2 Many kitchens have an exhaust fan. What mixtures would the filters above the stove separate?
Q3 What material are used in fish-tank filters. Which ones are the best to use?

Answer 1

Q1 some mixture of a difficult-to-separate solid (eg. small bits of sand) from a liquid