protons and neutrons are in the nucleus electrons surround the atom and i have no idea what positrons are i just know they arent in an atom so your answer is B and C
A colloid has the particles that have the ability to scatter light called the Tyndall effect named after the scientist named Tyndall. A suspension has large suspended particles that settle out at the bottom of the container. A solution has small particles that are evenly distributed throughout. Hence the answer is choice 2.
When dealing with making diluted solutions from concentrated solutions, we can use the following formula
c1v1 = c2v2
where c1 and v1 are the concentration and volume of the concentrated solution respectively.
c2 and v2 are the concentration and volume of the diluted solution respectively
substituting these values in the above formula,
20 mL x 0.200 M = C x 250.0 mL
C = 0.0160 M