What happens when a hot saturated solution is cooled?

Describe any three properties of colloids. Categorise the following examples of colloids into different categories of colloids: Jelly,fog,milk,shaving cream.

Colloids are quite stable. Name the process by which you can separate the components of a colloidal solution.

$(a)$ $7\, g$ of iron filings and $4\, g$ of sulphur powder is treated with dilute sulphuric acid at room temperature. Name the gas produced.
$(b)$ The same mixture is heated strongly,cooled and then treated with dilute sulphuric acid. Which gas would be produced?
$(c)$ What is the cause of this difference in results of chemical reaction in different conditions?

Crystallisation is a better technique than simple evaporation. Give one reason to justify the statement.

Based on which factor is a solution said to be dilute,concentrated,or saturated?