Question

Which of the following is a false statement?
A. Cell fluid is an example of sol.
B. Butter is an example of gel.
C. Hair cream is an example of an emulsion.
D. Cheese is an example of foam.

Answer 1

Hint: Based on the dispersed phase and dispersed medium, colloids are classified into 8 categories. In sols, foams, and emulsions liquid acts as a dispersed medium whereas in gels solid acts as a dispersed medium.

Complete step by step answer:
A colloid is a substance consisting of particles that are dispersed throughout another substance. The size of these particles is very small and does not pass through a semipermeable membrane.
Based on the dispersed phase and dispersed medium, colloids are classified into 8 categories.
They are Aerosols, solid aerosols, sols, gels, foams, emulsions, solid foams, and solid sols.
In a sol, solid particles are put in a continuous liquid to make the colloid. The dispersing medium is liquid and the dispersed phase is solid. Cell fluid contains many solid particles which are in a colloidal range flowing through it. So cell fluid is a sol.
In a gel, the dispersed medium is solid and the dispersed phase is a liquid. Butter is a gel.
In an emulsion, both the dispersed medium and dispersed phase are liquids. Hair cream is an example of water-oil type emulsion. So, hair cream is an emulsion.
In foam, the dispersed medium is liquid and the dispersed phase is a gas. But the cheese is solid.
Therefore, cheese is not an example of foam.

The answer is Option D is the false statement.

Note:
Do not confuse sols with aerosols. Sol is a colloid with solid particles in a liquid whereas Aerosol contains small particles of liquid dispersed in a gas. An aerosol is different from a solid aerosol. Solid aerosol contains solid particles dispersed in a gas. Be careful with the definitions of the colloids.