Which of the following statement is not true about colloidal solution ?

Question

$\begin{array}{1 1} \text{(a) These are visible under powerful microscope.} \\ \text{ (b) Their particles do not settle down with passage of time} \\ \text{ (c) Their particles are electrically charged.} \\ \text{(d) These are homogeneous in nature} \end{array}$