Question

Soap lather is an example of:
A) Foam
B) Sol
C) Emulsion
D) Gel

Answer 1

To solve this question, we must first understand the chapter of Surface Chemistry where you have studied about the type of colloidal solutions. Then we need to assess the information about the formation of those different kinds of colloidal solutions and then only we can conclude the correct answer.

Complete solution:
Before we move forward with the solution of this given question, let us first understand some basic concepts about colloids:
In a very manner, we can define colloids as a mixture where one of the substances is split into very minute particles which are dispersed throughout a second substance. The minute particles are known as colloidal particles.
Colloidal Solutions are divided into the following types:
Foam: Foam is a solution of a gas in a liquid. The substance being dispersed would be the gas, triggering the fluid to become frothy and foamy. A sample of this would be shaving cream.
Emulsion: An emulsion is a combination of liquids. It is basically when one liquid is consistently dispersed all through another liquid. A sample of this would be mayonnaise or milk.
Sol: The third form is called a sol. A sol is a combination of a solid that is evenly dispersed throughout a fluid. Samples of sols include paint, blood and silver aerosols.
Hydrocolloid: A hydrocolloid is a more detailed form of a colloidal solution. In this solution, the fluid of a precise material is properly disseminated in water.
Reversible or Irreversible Colloids: The colloidal solutions can be additionally labeled as being reversible or irreversible.
Since, in Soap dispersion medium is liquid and dispersed phase is gas.
And after going through the classification of colloidal solution as written above, we can simply conclude that Soap is an example of Foam.

So, clearly we can conclude that the correct answer is Option A.

Note: Colloidal systems can occur in any of the three key states of matter gas, liquid or solid. However, a colloidal solution usually refers to a liquid concoction. The primary distinguishing feature between a true solution and a colloidal solution is fundamentally the dimensions of the constituent parts.