NIOS Colloids Intext Questions With Answer

National Institute of Open Schooling (NIOS)
Sr. Secondary, Module-3
Lession-8: NIOS Colloids Intext Questions With Answer

INTEXT QUESTIONS 8.1

1. Classify the following into suspension, colloidal solution and true solution.
milk, sugar in water, clay in water, blood, boot polish, sand in water, face cream, jelly, foam.

Answer: Suspension:– Clay in water, Sand in water
Colloidal:– Milk, Blood, Boot polish, Face Cream, Jelly, Foam
True Solution:– Sugar in water

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2. Give one example each of
(a) Sol (b) Gel (c) Aerosol (d) Emulsion

Answer: Sol:– Starch in water
Gel:– Silica gel
Aerosol:– Fog
Emulsion:– Milk

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3. What is the difference between an alcosol and hydrosol?

Answer: Alcosol is a colloidal solution of a solid as dispersed phase in gas as Dispersion medium. Fog is an example of colloidal solution while in hydrosol water is the dispersion medium.

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4. How does colloidal solution differ from true solution.

Answer: True solution
1. Homogeneous in nature
2. Size of solute in less than 1 nm
3. Form transparent solution and allows light to pass through them
4. Donot show tyndall effect
Colloidal solution
1. Heterogeneous in nature
2. Particle size (1–100) nm
3. Form translucent solution and Path of light becomes visible
4. Show tyndall effect

INTEXT QUESTIONS 8.2

1. Name two colloids that can be prepared by Bredig's Arc method.

Answer: Gold sol, and Platinum sol can be prepared by Bredig's Arc method.

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2. Name two colloids that can be prepared by chemical methods.

Answer: As₂S₃ and Fe(OH)₃ (Arsenious sulphide sol, ferric hydroxide sol) can be prepared by chemical method.

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3. Differentiate between
(a) Lyophilic and Lyophobic sol.
(b) macromolecular and multimolecular colloids.

Answer: (a) Lyophilic Sol
1. easy to prepare
2. liquid-loving sols
3. affinity between dispersed phase and dispersion medium
4. reversible
Lyophobic Sol
1. special method used for preparation
2. liquid-hating sols
3. No affinity between the two phases
4. Not reversible
(b) Macromolecular:- The size of the colloidal particles large enough to fall in the colloidal dimensions.
Multimolecular:– Individually the particles are not of colloidal dimensions but they aggregate to join together to form molecules of colloidal size.

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4. Explain the formation of miscelle.

Answer: Micelles are formed when a substance having a polar end and a non-polar end are at a higher concentration. They need an aqueous medium to cumulate. The polar heads are faced outwards as the water is also polar in nature and therefore they interact and the centre point is formed due to the non-polar ends of all the substance.

NIOS Sr. Secondary Chemistry Intext Questions of All Chapters with Answer