chemistry : class12 Protein Colloids : Macromolecular colloids : Surface Chemistry MCQ Questions and Answers
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Protein Colloids
MCQ questions and answers.
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MCQ Questions
1. Proteins form which type of colloidal system when dispersed in water?
A.
Macromolecular colloids
B.
Multimolecular colloids
C.
Associated colloids
D.
Suspensions
Correct Answer:
Macromolecular colloids
Explanation:
Proteins are very large molecules, and their dispersions in water behave as macromolecular colloids.
2. Protein sols are generally classified as which type of colloids?
A.
Lyophilic colloids
B.
Lyophobic colloids
C.
Suspensions
D.
Coarse emulsions
Correct Answer:
Lyophilic colloids
Explanation:
Protein particles have a strong affinity for water, so protein sols are lyophilic colloids.
3. The stability of a protein sol in water is mainly due to the protein molecules being surrounded by:
A.
Solvent molecules
B.
Metal atoms
C.
Gas bubbles
D.
Insoluble crystals
Correct Answer:
Solvent molecules
Explanation:
Water molecules become associated with protein molecules, forming a solvated or hydrated layer that helps stabilize the protein sol.
4. What usually happens to a protein at its isoelectric point?
A.
It has zero net charge
B.
It becomes strongly positively charged
C.
It becomes strongly negatively charged
D.
It changes into a gas
Correct Answer:
It has zero net charge
Explanation:
At the isoelectric point, a protein carries no net electrical charge because its positive and negative charges balance each other.
5. At the isoelectric point, the stability of a protein sol generally becomes:
A.
Minimum
B.
Maximum
C.
Unchanged in every case
D.
Infinite
Correct Answer:
Minimum
Explanation:
At the isoelectric point, the protein has no net charge, so electrostatic repulsion between protein particles is least and aggregation is easier.
6. Which process is commonly used to separate small ions from a protein sol?
A.
Dialysis
B.
Distillation
C.
Sublimation
D.
Crystallisation of the protein
Correct Answer:
Dialysis
Explanation:
In dialysis, small ions pass through a semipermeable membrane while the larger protein particles are retained.
7. The movement of protein particles in an electric field depends mainly on their:
A.
Electrical charge
B.
Colour
C.
Melting point
D.
Odour
Correct Answer:
Electrical charge
Explanation:
Charged protein particles move toward the oppositely charged electrode during electrophoresis.
8. Adding a high concentration of an electrolyte to a protein sol may cause:
A.
Salting out of the protein
B.
Formation of a true solution of the protein
C.
Conversion of protein into a metal
D.
Permanent disappearance of water
Correct Answer:
Salting out of the protein
Explanation:
A high concentration of electrolyte removes water from hydrated protein molecules, which can cause the protein to separate from the sol.
9. Which property is characteristic of protein colloids in water?
A.
They have a strong affinity for the dispersion medium
B.
They are completely insoluble in water
C.
They always form precipitates immediately
D.
They contain only small ions
Correct Answer:
They have a strong affinity for the dispersion medium
Explanation:
Protein molecules interact strongly with water, which is why protein colloids are lyophilic and comparatively stable.
10. A protein molecule can carry a positive or negative charge depending mainly on the:
A.
pH of the medium
B.
Colour of the solution
C.
Shape of the container
D.
Pressure of the atmosphere only
Correct Answer:
pH of the medium
Explanation:
Changes in pH alter the ionisation of acidic and basic groups in the protein molecule, changing its net charge.
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