Answer:
Option D
Step-by-step explanation:
The complete question is
Which statement is true concerning colloids?
A. It carries a net electric charge
B. It consists of one phase only
C. It can be made out of two gases
D. It is electrically neutral as a whole
Solution
The particles with in the colloids are either positively or negatively charged due to presence of molecular electrolyte. The charged particles do not cluster together due to repulsion force. However, these charged particles align along two different layers - one positive layer and the other negative layer.
The net charge reduces to zero because of two forces in equal amount due to presence of equal number of positive and negative charges
Hence, option D is correct