91. Which of the following is true for an oil-in-water emulsion?
- a) Oil is the dispersion medium
- b) Water is the dispersion medium
- c) Water is the dispersed phase
- d) Neither oil nor water is involved
Answer: b) Water is the dispersion medium
Explanation: In an oil-in-water emulsion, oil is the dispersed phase, and water is the dispersion medium. Examples include milk and salad dressings.
92. Which of the following processes can be used to remove dissolved gases from colloidal solutions?
- a) Dialysis
- b) Ultrafiltration
- c) Boiling
- d) Adsorption
Answer: c) Boiling
Explanation: Boiling is used to remove dissolved gases from colloidal solutions. The heat causes the gases to escape from the solution.
93. Which of the following statements is true about the nature of colloidal solutions?
- a) They are always transparent
- b) They are homogeneous in nature
- c) They exhibit both the Tyndall effect and Brownian movement
- d) They do not scatter light
Answer: c) They exhibit both the Tyndall effect and Brownian movement
Explanation: Colloidal solutions exhibit both the Tyndall effect (scattering of light) and Brownian movement (random motion of particles), which are characteristic properties of colloids.
94. Which of the following colloidal systems has a liquid dispersed in a solid?
- a) Gel
- b) Foam
- c) Emulsion
- d) Aerosol
Answer: a) Gel
Explanation: In a gel, a liquid is dispersed in a solid. Examples of gels include jelly and certain cosmetics.
95. Which of the following is true regarding associated colloids?
- a) They are always lyophilic in nature
- b) They exhibit properties of both true solutions and colloidal solutions
- c) They can only exist in solid form
- d) They do not form micelles
Answer: b) They exhibit properties of both true solutions and colloidal solutions
Explanation: Associated colloids, such as soap solutions, exhibit the properties of both true solutions and colloidal solutions. They form micelles at higher concentrations.
96. The phenomenon of adsorption is used in:
- a) Removing gases from liquids
- b) Coagulation of colloidal particles
- c) Purification of colloidal solutions
- d) All of the above
Answer: d) All of the above
Explanation: Adsorption is a phenomenon used in various applications such as removing gases from liquids, coagulating colloidal particles, and purifying colloidal solutions by adsorbing impurities.
97. Which of the following statements is true for electrophoresis?
- a) It is the random movement of colloidal particles
- b) It is the movement of colloidal particles under an electric field
- c) It causes coagulation of colloidal solutions
- d) It does not affect the charge on colloidal particles
Answer: b) It is the movement of colloidal particles under an electric field
Explanation: Electrophoresis is the movement of colloidal particles towards the oppositely charged electrode under the influence of an electric field. It is used to study the charge on colloidal particles.
98. Which of the following is used to coagulate rubber from latex?
- a) Sulphuric acid
- b) Gelatin
- c) Sodium chloride
- d) Calcium chloride
Answer: a) Sulphuric acid
Explanation: Sulphuric acid is used to coagulate rubber from latex. The acid neutralizes the charge on the rubber particles, causing them to aggregate and form a solid mass of rubber.
99. Which of the following is an example of a colloidal system in which a gas is dispersed in a solid?
- a) Aerosol
- b) Gel
- c) Foam
- d) Solid foam
Answer: d) Solid foam
Explanation: Solid foam is a colloidal system where gas is dispersed in a solid. Examples include foam rubber and pumice stone.
100. Which of the following best describes coagulation?
- a) The breaking up of a colloidal solution into smaller particles
- b) The formation of colloidal particles from a true solution
- c) The process of settling of colloidal particles after neutralization of charge
- d) The continuous scattering of light in a colloidal solution
Answer: c) The process of settling of colloidal particles after neutralization of charge
Explanation: Coagulation is the process where colloidal particles settle down after their charge has been neutralized, usually by the addition of an electrolyte.
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