chemistry : class12 Sulphide Ore Concentration : Concentration of ores : General Principles and Processes of Isolation of Elements MCQ Questions and Answers
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Sulphide Ore Concentration
MCQ questions and answers.
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MCQ Questions
1. Which method is commonly used for concentrating sulphide ores?
A.
Froth flotation
B.
Hand picking
C.
Magnetic separation
D.
Hydraulic washing
Correct Answer:
Froth flotation
Explanation:
Froth flotation is commonly used to concentrate sulphide ores because the sulphide particles are preferentially wetted by oil and attach to the froth.
2. In the froth flotation process, sulphide ore particles are preferentially wetted by which substance?
A.
Water
B.
Oil
C.
Sand
D.
Acid
Correct Answer:
Oil
Explanation:
Sulphide ore particles are preferentially wetted by oil, allowing them to attach to air bubbles and rise as froth.
3. What is the main purpose of frothers in the froth flotation process?
A.
To form a stable froth
B.
To dissolve the ore
C.
To remove magnetic impurities
D.
To increase the density of gangue
Correct Answer:
To form a stable froth
Explanation:
Frothers help produce a stable froth that carries the oil-coated sulphide ore particles to the surface.
4. Which of the following is commonly used as a collector in the froth flotation of sulphide ores?
A.
Xanthate
B.
Sodium chloride
C.
Calcium carbonate
D.
Potassium nitrate
Correct Answer:
Xanthate
Explanation:
Xanthates act as collectors by making sulphide ore particles water-repellent and helping them attach to air bubbles.
5. During froth flotation, which particles rise to the surface with air bubbles?
A.
Oil-coated sulphide ore particles
B.
Uncoated gangue particles
C.
Water molecules
D.
Dissolved salts
Correct Answer:
Oil-coated sulphide ore particles
Explanation:
The collector coats sulphide ore particles with oil, so they attach to air bubbles and rise to the surface as froth.
6. What is the role of a depressant in the froth flotation process?
A.
It prevents a selected ore from forming froth
B.
It increases the amount of gangue
C.
It melts the sulphide ore
D.
It converts ore into a gas
Correct Answer:
It prevents a selected ore from forming froth
Explanation:
A depressant selectively prevents one sulphide mineral from being collected in the froth, allowing separation of different sulphide ores.
7. In the separation of galena and zinc sulphide ores, which substance can act as a depressant for zinc sulphide?
A.
Sodium cyanide
B.
Pine oil
C.
Xanthate
D.
Copper sulphate
Correct Answer:
Sodium cyanide
Explanation:
Sodium cyanide depresses zinc sulphide, while galena can be collected by froth flotation under suitable conditions.
8. Which part of the froth flotation apparatus contains the concentrated sulphide ore?
A.
The froth collected at the surface
B.
The bottom layer of water only
C.
The solid walls of the tank
D.
The air inlet pipe
Correct Answer:
The froth collected at the surface
Explanation:
The concentrated sulphide ore particles rise with air bubbles and are collected from the froth at the surface.
9. Why is froth flotation especially suitable for sulphide ores?
A.
Sulphide particles can be selectively wetted by oil
B.
Sulphide particles are always magnetic
C.
Sulphide ores dissolve completely in water
D.
Sulphide ores have the lowest density
Correct Answer:
Sulphide particles can be selectively wetted by oil
Explanation:
Selective wetting by oil makes sulphide particles attach to air bubbles, separating them from water-wetted gangue.
10. In froth flotation, the unwanted earthy impurities associated with the ore are called what?
A.
Gangue
B.
Flux
C.
Slag
D.
Matte
Correct Answer:
Gangue
Explanation:
Gangue refers to the unwanted earthy or rocky impurities separated from sulphide ore during concentration.
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