How is measuring the volume of liquids different than measuring the volume of regular-shaped solids?

When molecules of water vapor in the air come in contact with a cold can of soft drink , they lose energy ,slow down, and form a liquid due to decrease in ?

In which situation can a mixture always be called a solution

In the millikan oil drop experiment they determined that every drop had a charge which was a while number multiple of -1.60x10^-19. if a drop has a total charge of -9.60x10^-19 then how many excess electrons are contained within the drop?