a: The heterogeneous mixture that has very small dispersed particles and stays mixed for a long time is colloid. Because colloid has particles that are small enough to suspended but are as large that they can scatter light.
b: A heterogeneous mixture that has large dispersed particles that settle over time is a suspension. Suspension can occur in liquids or gases but not in solids. There particles settle down slowly over time.
When two substances that cannot dissolve each other are mixed, a mixture is formed. a heterogeneous mixture that has very small dispersed particles and stays mixed for a long time is a "Colloid"
An example of colloid can be gels, sols, or emulsions; where solids or liquids are dispersed in the mixture. It usually takes very long time to settle down.
A heterogeneous mixture that has larger dispersed particles that settle over time is a "Suspension"
Suspensions are those mixtures which usually has large particles and which takes comparatively less time than colloids to get settled. Like salt water, muddy water, fine sand in water, etc.
