chemistry : class12 Collectors : Concentration of ores : General Principles and Processes of Isolation of Elements MCQ Questions and Answers
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Collectors
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MCQ Questions
1. What is the main function of a collector in the froth flotation process?
A.
To make selected mineral particles water-repellent
B.
To dissolve the ore completely
C.
To increase the density of gangue
D.
To convert the ore into a gas
Correct Answer:
To make selected mineral particles water-repellent
Explanation:
Collectors selectively coat the desired mineral particles and make them hydrophobic, so they attach to air bubbles and rise with the froth.
2. Which of the following is commonly used as a collector in the froth flotation of sulphide ores?
A.
Sodium ethyl xanthate
B.
Pine oil
C.
Sodium chloride
D.
Calcium carbonate
Correct Answer:
Sodium ethyl xanthate
Explanation:
Sodium ethyl xanthate is a commonly used collector for sulphide ores because it makes the sulphide mineral particles water-repellent.
3. Collectors used in froth flotation generally make the selected ore particles:
A.
Hydrophobic
B.
Highly soluble in water
C.
Heavier than gangue particles
D.
Chemically inert toward air
Correct Answer:
Hydrophobic
Explanation:
A collector gives the selected mineral particles a water-repellent, or hydrophobic, surface that helps them attach to air bubbles.
4. Which property of mineral particles is increased by the action of a collector?
A.
Affinity for air bubbles
B.
Solubility in water
C.
Melting point
D.
Electrical resistance of gangue
Correct Answer:
Affinity for air bubbles
Explanation:
Collectors make the desired mineral particles hydrophobic, increasing their tendency to attach to air bubbles in froth flotation.
5. In froth flotation, a collector is added mainly to:
A.
Selectively concentrate the desired mineral
B.
Remove all water from the ore
C.
Increase the temperature of the slurry
D.
Break the mineral into atoms
Correct Answer:
Selectively concentrate the desired mineral
Explanation:
The collector selectively changes the surface of the desired mineral, allowing it to be separated from gangue through the froth.
6. Which of the following substances acts as a collector rather than a frother in froth flotation?
A.
Ethyl xanthate
B.
Pine oil
C.
Water
D.
Air
Correct Answer:
Ethyl xanthate
Explanation:
Ethyl xanthate acts as a collector by making sulphide mineral particles hydrophobic, whereas pine oil is commonly used as a frother.
7. Collectors are especially useful in the concentration of:
A.
Sulphide ores
B.
Pure water
C.
Non-mineral gases
D.
Organic liquids
Correct Answer:
Sulphide ores
Explanation:
Collectors such as xanthates are widely used in froth flotation to concentrate sulphide ores.
8. What happens when a collector coats the particles of a sulphide mineral?
A.
The particles become water-repellent
B.
The particles become completely soluble in water
C.
The particles turn into gangue
D.
The particles lose their mineral identity
Correct Answer:
The particles become water-repellent
Explanation:
The collector forms a coating that makes sulphide mineral particles hydrophobic, helping them rise with air bubbles in the froth.
9. Which of the following is a characteristic feature of a collector?
A.
It acts selectively on the desired mineral particles
B.
It dissolves every component of the ore equally
C.
It prevents all particles from contacting air
D.
It changes gangue into a metal directly
Correct Answer:
It acts selectively on the desired mineral particles
Explanation:
Collectors are selected so that they preferentially coat the desired mineral particles and help separate them from gangue.
10. The use of a collector in froth flotation helps the desired mineral particles to:
A.
Float with the froth
B.
Settle immediately at the bottom
C.
Evaporate from the slurry
D.
Become chemically identical to gangue
Correct Answer:
Float with the froth
Explanation:
By making the desired particles hydrophobic, collectors enable them to attach to air bubbles and float to the surface with the froth.
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