General Principles and Processes of Isolation of Elements Test

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General Principles and Processes of Isolation of Elements Test - 10

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Weekly Quiz Competition

Question 1
1 / -0

In the context of the Hall - Heroult process for the extraction of Al, which of the following statements is false?

A
$$CO$$ and $$CO_2$$ are produced in this process

B
$$Al_2O_3$$ is mixed with $$CaF_2$$ which lowers the melting point of the mixture and brings conductivity

C
$$Al^{3+}$$ is reduced at the cathode to $$Al$$

D
$$Na_3AlF_6$$ serves as the electrolyte

Solution

In the Hall - Heroult process for the extraction of $$Al$$, the electrolyte used is a fused mixture of alumina (2-8%, synthetic cryolite $$Na_3AlF_6$$ (80-85%), $$AlF_3$$ (5-7%) and fluorspar, $$CaF_2 $$ (5-7%).
Question 2
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Which one of the following ores is best concentrated by froth floatation method?

A
Siderite

B
Galena

C
Malachite

D
Magnetite

Solution

$$Explanation\ for \ correct\ option:$$

In the Froth floatation method, the finely ground ore is mixed with water, oil and foam foaming agent.

Then the mixture is stirred, during stirring foam is gets formed which contains ore. The ore comes out with foam and heavily dense impurities remain bottom of the container.

The froth floatation method is useful for low dense ores. Therefore Galena (i.e. $$PbS$$) is low dense and can be separated by this method.

$$Explanation\ for \ incorrect\ option:$$

Siderite ( $$FeCO_3$$), Malachite ($$Cu_2CO_3(OH)_2$$) and Magnetite ($$Fe_3O_4$$) are dense ores and not suitable for froth floatation method.

$$Final\ Answer:$$ Option $$B$$.
Question 3
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The refining method used when the metal and the impurities have low and high melting temperatures, respectively, is :

A
zone refining

B
liquation

C
distillation

D
vapour phase refining

Solution

$$\rightarrow $$ metal with low melting point containing impurities of high melting point can be purified by liquation because

$$\rightarrow $$ Liquation separation is based on differences in the melting point and density of alloy and on the low level of mutual solubility of the constituents.

So, option 2 is correct.
Question 4
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The correct statement is :

A
leaching of bauxite using concentrated $$NaOH$$ solution gives sodium aluminate and sodium silicate

B
The blistered appearance of copper during the metallurgical process is due to the evolution of $$CO_2$$

C
pig iron is obtained from cast iron

D
the Hall-Heroult process is used for the production of aluminium and iron.

Solution

(1) During leaching when bauxite is treated with concentrated $$NaOH$$, then sodium aluminate and sodium silicate is formed in the soluble form, whereas $$Fe_2O_3$$ is precipitated.

(2) The blistered appearance of copper during the metallurgical process is due to the evolution of $$SO_2$$.

(3) Cast iron is obtained from pig iron.

(4) Hall-Heroult process is used for the production of only aluminium.
Question 5
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Which one of the following ores is best concentrated by froth-floatation method?

A
Magnetite

B
Cassiterite

C
Galena

D
Malachite

Solution

Galena ($$PbS$$) is best concentrated by a froth-floatation method.
This method is used for the concentration of sulphide ores such as galena ($$PbS$$), zinc blende ($$ZnS$$) and copper pyrite $$(CuFeS_2)$$.

Hence, the correct option is $$C$$

Question 6

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Match items of Column I with the items of Column II and assign the correct code:

	Column I		Column II
(a)	Cyanide process	(i)	Ultrapure $$Ge$$
(b)	Froth floatation process	(ii)	Dressing of $$ZnS$$
(c)	Electrolytic reduction	(iii)	Extraction of $$Al$$
(d)	Zone refining	(iv)	Extraction of $$Au$$
		(v)	Purification of $$Ni$$

a - (iv), b - (ii), c - (iii), d - (i)

a - (ii), b - (iii), c - (i), d - (v)

a - (i), b - (ii), c - (iii), d - (iv)

a - (iii), b - (iv), c - (v), d - (i)

Solution

Cyanide process is used for the extraction of $$Au$$ and $$Ag$$.

Froth flotation process is used for dressing of $$ZnS$$. This process is used for sulphide ores.

Electrolytic reduction is used in the extraction of $$Al$$.

Zone refining is used to obtain ultrapure $$Ge$$.

The correct code for a, b, c and d are respectively, (iv), (ii), (iii), (i).

Question 7
1 / -0

Considering Ellingham diagram, which of the following metals can be used to reduced alumina?

A
$$Mg$$

B
$$Fe$$

C
$$Cu$$

D
$$Zn$$

Solution

Considering Ellingham diagram, $$Mg$$ metal can be used to reduced alumina.
The negative free energy change for the formation of $$\displaystyle MgO$$ from $$Mg$$ is greater than that for the formation of $$\displaystyle Al_2O_3$$ from $$Al$$.

Hence, $$Mg$$ has greater tendency to undergo oxidation than $$Al$$. Hence, $$Mg$$ is oxidised and $$Al_2O_3$$ is reduced to $$Al$$.

Note: More negative the value of $$\displaystyle \Delta G$$, the greater is the tendency, of the element to combine with oxygen.
Question 8
1 / -0

Bell metal is an alloy of:

A
Sn and Pb

B
Cu and Pb

C
Sn and Cu

D
Fe, Sn and Cu

Solution

Bell metal is a hard alloy used for making bells and related instruments, such as cymbals. It is a form of bronze, usually in approximately a 4:1 ratio of copper to tin. Bell metal ore is a sulfide of tin, copper, and iron called stannite.
Question 9
1 / -0

Semiconductor materials like $$Si$$ and $$Ge$$ are usually purified by:

A
distillation

B
zone refining

C
liquation

D
electrolytic refining

Solution

Semiconductor materials like $$Si$$ and $$Ge$$ are usually purified by zone refining. Zone refining is based on the principle of fractional crystallisation. Due to differences in solubilities of impurities in solid and molten states of metal, the zones of impurities are formed and finally removed.
Question 10
1 / -0

Cinnabar is an ore of :

A
Hg

B
Cu

C
Pb

D
Zn

Solution

Cinnabar HgS is an ore of Hg.

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Re-Attempt Weekly Quiz Competition

General Principles and Processes of Isolation of Elements Test - 10

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General Principles and Processes of Isolation of Elements Test - 10

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Question 1

$$CO$$ and $$CO_2$$ are produced in this process

$$Al_2O_3$$ is mixed with $$CaF_2$$ which lowers the melting point of the mixture and brings conductivity

$$Al^{3+}$$ is reduced at the cathode to $$Al$$

$$Na_3AlF_6$$ serves as the electrolyte

Solution

Question 2

Siderite

Galena

Malachite

Magnetite

Solution

Question 3

zone refining

liquation

distillation

vapour phase refining

Solution

Question 4

leaching of bauxite using concentrated $$NaOH$$ solution gives sodium aluminate and sodium silicate

The blistered appearance of copper during the metallurgical process is due to the evolution of $$CO_2$$

pig iron is obtained from cast iron

the Hall-Heroult process is used for the production of aluminium and iron.

Solution

Question 5

Magnetite

Cassiterite

Galena

Malachite

Solution

Question 6

a - (iv), b - (ii), c - (iii), d - (i)

a - (ii), b - (iii), c - (i), d - (v)

a - (i), b - (ii), c - (iii), d - (iv)

a - (iii), b - (iv), c - (v), d - (i)

Solution

Question 7

$$Mg$$

$$Fe$$

$$Cu$$

$$Zn$$

Solution

Question 8

Sn and Pb

Cu and Pb

Sn and Cu

Fe, Sn and Cu

Solution

Question 9

distillation

zone refining

liquation

electrolytic refining

Solution

Question 10

Hg

Cu

Pb

Zn

Solution

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