Question

A colloidal dispersion differs from a suspension in that colloidal particles in a dispersion

Group of answer choices

do not settle at an appreciable rate

too small to scatter light

tend to settle at an appreciable rate

are large enough to be seen with the naked eye

Answer 1

Colloidal dispersion is a heterogeneous mixture in which solute particles (dispersed phase) have size of the order 1-1000 nm (1 nm=10-9 m). These solute particles cannot be seen by naked eyes. These dispersed particles don't settle down in the mixture and hence this is a stable mixture. The size of colloidal particles is such that these can scatter light. This is called Tyndall effect.

Suspension is a heterogeneous mixture in which solute particles have size greater than 1000 nm. These solute particles are large enough to be seen by the naked eyes and they settle down over a period of time and hence this mixture is unstable. Suspension may scaller light if the number of solute particles is not large enough, in which case the suspension doesn't allow light to pass through.

So a colloidal dispersion differs from a suspension in that the colloidal particles don't settle down at an appreciable rate. On the other hand suspended particles in a suspension settle down at an appreciable rate.