Comment on the statement that "colloid is not a substance but a state of substance".  

Explanation

"Colloids is not a substance but a state of substance" is a true statement. Because there are some substances which are crystalloid under certain conditions but colloid under the other, e.g., NaCl is such substance which is called a crystalloid and behaves as a crystalloid in aqueous medium. But when mixed with benzene, it behaves as colloids. So, the above statement is correct.
Moreover, the diameter of colloidal particles range from 1 to 1000 nm. If particle diameter is lesser than 1 nm, the solution is true solution and if it is more than 1000 nm, the solution is a suspension. The colloidal state is an intermediate state between these two.