Question

What is the size of colloidal particles?

(a) 10-20 nm

(b) More than 20 nm

(c) Less than 10 nm

(d) 30 to 50 nm

The question was asked in an internship interview.

Origin of the question is Colloids in chapter Surface Chemistry of Engineering Chemistry II

Answer 1

Correct option is (a) 10-20 nm

For explanation I would say: Since colloidal are intermediate between powdered particles and suspension particles, they have a size in between these particles of about 10 to 20 nm. These are considered to be intermediate size of molecules.