Question

The main characteristics of colloidal solution are

(i) It shows the Tyndall effect

(ii) Its size is between 10 to 100 nm

(iii) Heterogenous

(iv) Generally clear and transparent

• A. (i), (ii) and (iii)
• B. (i) and (iii)
• C. (i) (ii) and (iii)
• D. (i), (iii) and (iv)

Answer 1

The correct option is B

(i) and (iii)

The explanation for the correct option:

The colloidal solution shows the Tyndall effect:

1. A colloidal solution is a solution in which the size of solute particles is intermediate between those in true solution and suspension.
2. Example: Blood and milk.
3. The Tyndall effect, also known as the Tyndall phenomenon, is the scattering of a light beam by a medium containing tiny suspended particles.
4. Colloids include particles that scatter light as it passes through them, exhibiting the Tyndall effect.

A colloidal solution is heterogeneous:

1. A mixture is said to be a heterogeneous mixture if it consists of two or more parts ( called phases ) which have different compositions.
2. The colloidal solution consists of two phases: the dispersed phase and the dispersion medium.
3. The component which is present in small proportion and consists of particles of colloidal dimensions (${10}^{-9}\mathrm{m}\mathrm{to}{10}^{-7}\mathrm{m}$ ) is called the dispersion phase and it is like solute in solution while the component which is present in excess and acts as a medium in which colloidal particles are dispersed and it is like a solvent in the solution is called dispersion medium.
4. Due to the presence of small size particles as compared to the suspension, the mixture appears to be homogeneous but it is a heterogeneous mixture.

Since out of all statements only (i) and (iii) are correct thus option (b) is correct.

The explanation for incorrect options:

Its size is between 10 to 100 nm:

The size of the particles is $1\mathrm{to}100\mathrm{nm}$ thus, the option is correct.

A colloidal solution is clear and transparent:

They are not completely transparent; rather, they are translucent.

Since statements (ii) and (iv) are incorrect thus options (a), (c) and (d) are incorrect.

Hence option (b) is the correct option.