Question

Examples of lyophobic colloids are:
A. RBC
B. metal sulphide sols
C. smoke
D. albumin

Answer 1

Hint: To generally determine whether a mixture is a colloid or not we can use Tyndall Effect. When a source light is shined through a true solution, the substance in the dispersed phases scatters the light in all directions, making it readily seen.

Complete step by step solution:
Colloids are a mixture in which microscopic particles of one substance (called colloidal particles) are dispersed throughout a second substance. The particles are larger in comparison to those found in solution, but are too small to be seen with a microscope. The size of colloidal particles generally varies between ${{10}^{-7}}$ cm to ${{10}^{-5}}$ cm in size.

Based on interactions colloids are of two types:
1.) Lyophilic colloids are thermodynamically stable colloids that love solvents. They are highly viscous and have a strong attraction force between colloids and the liquid. Lyophilic colloids are stable because of strong forces of attraction between colloidal particles and solvents.
For example: Solutions of organic substances such as starch, gelatin, proteins and certain polymers in organic solvents.
2.) Lyophobic colloids are thermodynamically unstable colloids that hate solvent. They have the same viscosity as the solvent and there is less or no attraction force between colloids and the liquid.
For example: Solutions of inorganic substances such Arsenic ($A{{l}_{2}}S{{O}_{3}}$), Iron $Fe{{(OH)}_{3}}$, Platinum and sulphides and oxides of various metals.

So, the correct option is (b).

Note: Lyophilic colloids are very difficult to coagulate due to their stable nature. They are also known as intrinsic colloids. Specialized coagulation methods are required to settle down these particles.