Question

A colloid is the dividing line between solutions and heterogenous mixtures.
What is the exact particle size of a colloid compared to the exact particle size of a solution.

A. over 1000nm compared to 0.1-1nm
B. 1-1000nm compared to 0.01-1nm
C. 0.10-1nm compared to 1-1000nm
D. 100nm compared to 1-100nm

I chose A but that was wrong so I was thinking it was B because it should be smaller than 1000nm but not sure.

Answer 1

I really have no idea how to answer this question. What is meant by size? Is that radius, diameter, spherical area, just what. First, I think you can eliminate C because it goes from small to large and the question calls for colloid to solution size. You know colloid must be larger. You already know A is not right. That leaves just B and D so that's a 50-50 chance at this point. I looked on the web and the articles I read don't define size any better but here is one that comes the closest to putting some limits on it at 1 nm to 1 micrometer. That would be 1 nm to 1000 nm which makes B in that range. I couldn't find anything about "size of atoms" That's nebulous anyway since electrons are in a probable zone. Here is the one site I thought might be worth considering.
http://old.iupac.org/reports/2001/colloid_2001/manual_of_s_and_t/node33.html