Question

What type of mixture scatters light and cannot be filtered?

Answer 1

Heterogeneous mixture called as colloidal solution, can scatter beam of light passing through it and renders it's path visible.
The particles of colloidal can pass through filter paper. So, a colloidal cannot be separated by filtration.
Example : ink solution.
Soap solution.
Milk( emulsion)

Answer 2

colloidal solution, can scatter beam of light passing through it and makes the path of light visible.
colloidal particles  cannot be separated by filtration.

Example :
Starch solution.
Milk