61. Which of the following is an example of an oil-in-water emulsion?
- a) Butter
- b) Cold cream
- c) Milk
- d) Hair cream
Answer: c) Milk
Explanation: Milk is an oil-in-water emulsion, where tiny droplets of fat are dispersed in water. Butter and cold cream, on the other hand, are water-in-oil emulsions.
62. Which of the following colloids is classified as a lyophobic colloid?
- a) Starch sol
- b) Protein sol
- c) Sulphur sol
- d) Gelatin
Answer: c) Sulphur sol
Explanation: Lyophobic colloids (solvent-hating) like sulphur sol have little affinity for the dispersion medium and are not stable. They are less stable and require stabilizing agents, unlike lyophilic colloids like starch and protein sols.
63. In which of the following processes is a colloid converted into a sol?
- a) Peptization
- b) Coagulation
- c) Sublimation
- d) Adsorption
Answer: a) Peptization
Explanation: Peptization is the process by which a precipitate is converted into a colloidal sol by adding a small amount of electrolyte, which causes the dispersion of particles into colloidal size.
64. Which of the following factors does not affect the Tyndall effect?
- a) Wavelength of light used
- b) Size of colloidal particles
- c) Concentration of colloidal particles
- d) Nature of the colloid
Answer: d) Nature of the colloid
Explanation: The Tyndall effect depends on the wavelength of light, the size of the colloidal particles, and their concentration. The specific nature of the colloid does not directly affect the scattering of light.
65. Which of the following statements is true for a lyophilic colloid?
- a) They are irreversible
- b) They can be easily coagulated by electrolytes
- c) They show high viscosity
- d) They are unstable in the presence of a small amount of electrolyte
Answer: c) They show high viscosity
Explanation: Lyophilic colloids (solvent-loving) form stable solutions and exhibit high viscosity due to the strong affinity between the colloidal particles and the dispersion medium. They are generally reversible and stable in the presence of electrolytes.
66. Which of the following phenomena is used to distinguish between a colloidal solution and a true solution?
- a) Brownian movement
- b) Tyndall effect
- c) Coagulation
- d) Electrophoresis
Answer: b) Tyndall effect
Explanation: The Tyndall effect, which is the scattering of light by colloidal particles, can be used to distinguish between a colloidal solution and a true solution, as true solutions do not scatter light.
67. Which of the following methods cannot be used for the preparation of colloids?
- a) Peptization
- b) Ultrafiltration
- c) Condensation
- d) Dispersion
Answer: b) Ultrafiltration
Explanation: Ultrafiltration is used for the purification of colloidal solutions, not for their preparation. Colloids can be prepared by peptization, condensation, and dispersion methods.
68. Which of the following is not an example of a colloidal solution?
- a) Soap solution
- b) Sugar solution
- c) Blood
- d) Milk
Answer: b) Sugar solution
Explanation: A sugar solution is a true solution, where the solute (sugar) completely dissolves in the solvent (water). Soap solution, blood, and milk are examples of colloidal solutions.
69. Which of the following methods can be used to destroy the charge on colloidal particles, leading to coagulation?
- a) Adding a protective colloid
- b) Boiling the sol
- c) Decreasing temperature
- d) Addition of more solvent
Answer: b) Boiling the sol
Explanation: Boiling a colloidal solution can reduce the charge on colloidal particles, leading to coagulation. This is because the heat disrupts the stabilization caused by the charge, allowing the particles to aggregate.
70. In the Hardy-Schulze rule, the coagulating power of an ion increases with:
- a) Its size
- b) Its charge
- c) Its solubility
- d) Its molecular weight
Answer: b) Its charge
Explanation: According to the Hardy-Schulze rule, the greater the charge on the ions, the greater their ability to coagulate colloids. Highly charged ions neutralize the charge on colloidal particles more effectively, causing coagulation.
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