General Principles and Processes of Isolation of Elements Test

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General Principles and Processes of Isolation of Elements Test - 23

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Weekly Quiz Competition

Question 1
1 / -0

Which of the following method used for the concentration of copper pyrites?

A
Magnetic seperation

B
Gravity seperation

C
Froth Floatation process

D
None

Solution

This method is used when a higher ore contains impurities with higher density. This method is used for the concentration of Sulphide ores. (Eg: Copper pyrites, iron pyrites, Galena, Zinc blende etc.) Copper is mainly extracted from copper pyrites. After the concentration of its ore by froth flotation process, the ore is roasted in a current of air to remove arsenic, antimony and much of sulphur.
Question 2
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Electrolytic reduction of alumina to aluminium by Hall-Heroult's process is carried out _____________.

A
in the presence of sodium chloride

B
in the presence of flourite

C
in the presence of cryolite which forms a melt with lower melting temperature

D
in the presence of cryolite which forms a melt with higher melting temperature

Solution

Hint: The melting point of alumina is very high, and the electrolytic reduction must be carried out in a molten state.

Correct answer: Option $$C$$

Explanation:
Since the melting point of alumina is very high ($$2350\ K$$), it is very difficult and costly to melt alumina for the purposes of electrolytic reduction. However, on adding cryolite ($$Na_3AlF_6$$), the melting point decreases to below $$1000\ K$$ and this reduces the cost of the process. Cryolite also improves the electrical conductivity of the melt for better electrolytic reduction.
Question 3
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Froth floatation process for the concentration of ores is an illustration of physical phenomenon of:

A
adsorption

B
absorption

C
conagulation

D
sedimentation

Solution

Froth flotation is a highly versatile method for physically separating particles based on differences in the ability of air bubbles to selectively adhere to specific mineral surfaces in a mineral/water slurry. So, its a physical phenomenon of adsorption.
Question 4
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Collectors are the substances which combine with sulphide ore and make them water repellant. Which of the following substance can act as collector?

A
Sodium ethyl xanthate

B
Sodium xenate

C
Sodium pyrophosphate

D
Adsorption

Solution

Sodium ethyl xanthate is used as collector in froth floatation process.
Question 5
1 / -0

In froth-flotation process, pine oil functions as a(an):

A
activator

B
frothing agent

C
collector

D
agitator

Solution

In the froth-flotation process, pine oil functions as a frothing agent or foaming agent. Other frothing agents include eucalyptus oil, xanthates or fatty acids. The frothing agent forms a foam (or froth) with air.

Hence, the correct option is $$\text{B}$$
Question 6
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What is the principle of zone refining of metals?

A
Greater mobility of the pure metal than that of the impurity

B
Higher melting point of the impurity than that of the pure metal

C
Greater noble character of the solid metal than that of the impurity

D
Greater solubility of the impurity in the molten state than in the solid

Solution

Zone refining is based upon fractional crystallization as the impurity prefers to stay in the melt and on solidification only pure metals solidifies on the surface of melt.
In this process solubility of the impurities in the metal in molten is greater than in solid.
Question 7
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Which one of the following ores is best concentrated by froth flotation method?

A
Galena

B
Cassiterite

C
Magnetie

D
Malachite

Solution

Froth flotation method is used for removing gangue from sulphite ores.
Galena is PbS, Cassiterite is $$SnO_2$$, Magnetite is $$Fe_3O_4$$ and Malachite is $$CuCO_3.Cu(OH)_2$$.
Question 8
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Which of the following process is used for concentration of ore?

A
Froth flotation

B
Electrolytic methods

C
Smelting

D
Hoop's process

Solution

Froth flotation method is used for the concentration of sulphide ores.

The method is based on the preferential wetting properties with the frothing agent and water. In the given options, Galena (PbS) is the only sulphide ore.

Hence, option A is correct.
Question 9
1 / -0

An ore of tin containing $$FeCrO_4$$ is concentrated by:

A
magnetic separation

B
froth floatation

C
electrostatic

D
gravity separation

Solution

$$FeCrO_4$$ is magnetic ore so magnetic separation method is used for separation.
Question 10
1 / -0

Ellingham diagram represents:

A
Change of $$\Delta G $$ with temperature

B
Change of $$\Delta H $$ with temperature

C
Change of $$\Delta G $$ with pressure

D
Change of $$(\Delta G- T\Delta S) $$ with temperature

Solution

An Ellingham diagram is a graph showing the temperature dependence of the stability for compounds. This analysis is usually used to evaluate the ease of reduction of metal oxides and sulphides.
Ellingham diagram represents change in free energy $$\Delta G$$ with temperature.

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General Principles and Processes of Isolation of Elements Test - 23

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General Principles and Processes of Isolation of Elements Test - 23

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SHARING IS CARING

Question 1

Magnetic seperation

Gravity seperation

Froth Floatation process

None

Solution

Question 2

in the presence of sodium chloride

in the presence of flourite

in the presence of cryolite which forms a melt with lower melting temperature

in the presence of cryolite which forms a melt with higher melting temperature

Solution

Question 3

adsorption

absorption

conagulation

sedimentation

Solution

Question 4

Sodium ethyl xanthate

Sodium xenate

Sodium pyrophosphate

Adsorption

Solution

Question 5

activator

frothing agent

collector

agitator

Solution

Question 6

Greater mobility of the pure metal than that of the impurity

Higher melting point of the impurity than that of the pure metal

Greater noble character of the solid metal than that of the impurity

Greater solubility of the impurity in the molten state than in the solid

Solution

Question 7

Galena

Cassiterite

Magnetie

Malachite

Solution

Question 8

Froth flotation

Electrolytic methods

Smelting

Hoop's process

Solution

Question 9

magnetic separation

froth floatation

electrostatic

gravity separation

Solution

Question 10

Change of $$\Delta G $$ with temperature

Change of $$\Delta H $$ with temperature

Change of $$\Delta G $$ with pressure

Change of $$(\Delta G- T\Delta S) $$ with temperature

Solution

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