The role of cryolite in the metallurgy of aluminium is :

1. To decrease the melting point of the mixture from 2323 K to 1140 K
2. To increase the electrical conductivity of Al2O3
3. To decrease the electrical conductivity of Al2O3
4. Both '1' and '2'

Subtopic:  Metallurgy of individual elements |
 82%
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Leaching of low-grade copper ores does not involve

1. Cu getting converted into Cu2+(aq) in acidic medium

2. Cu getting converted into Cu2+(aq) in basic medium

3. Cu2+(aq) getting reduced to Cu

4. using bacteria in the presence of air.

 

Subtopic:  Intro - Flux, Leaching, Roasting & Calcination |
 51%
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Zinc cannot be extracted from zinc oxide via CO reduction because:

(Given:  Ellingham diagram)

 

1.  \(\Delta G_{f}^{o} \) of Zn from ZnO is lower than that of CO2 from CO
2.  \(\Delta G_{f}^{o} \) of ZnO from Zn is lower than that of CO2 from CO
3. ZnO is less stable than CO
4. ZnO is more stable than CO

Subtopic:  Ellingham Diagram |
 56%
From NCERT
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The value of fGO for the formation of Cr2O3 is – 540 kJmol−1and that of Al2O3  is – 827 kJ mol−1. The correct statement is-

1. Cr can reduce Al2O3 to Al

2. Cr2O3 cannot reduce Al2O3 to Al

3. Al can reduce Cr2O3 to Cr

4. Al cannot reduce Cr2O3 to Cr

Subtopic:  Metallurgy of individual elements |
 68%
From NCERT
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The better reducing agent for ZnO is: 

1. C

2. CO

3. CO2

4. CO32-

Subtopic:  Ellingham Diagram |
 60%
From NCERT
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The process in which Cl2 is obtained as a by-product is :

1. In the electrolysis of aqueous HCl, Cl2 is obtained at the cathode as a by-product. 
2. In the electrolysis of aqueous NaCl, Cl2 is obtained at the cathode as a by-product.
3.  In the electrolysis of molten NaCl, Cl2 is obtained at the anode as a by-product. 
4. None of the above

Subtopic:  Intro - Flux, Leaching, Roasting & Calcination |
 69%
From NCERT
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Al can reduce MgO under the following conditions:

1. Above 500 °C, Al can reduce MgO

2. Below 500 °C, Al can reduce MgO

3. Below 1350 °C, Al can reduce MgO

4. Above 1350 °C, Al can reduce MgO

Subtopic:  Ellingham Diagram |
 70%
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Consider the following statements:

a. Zone refining method is useful for producing semiconductors and other metals of very high purity.
b. Zone refining method is based on the principle that "the impurities are less soluble in the melt than in the solid-state of the metal".
c.

In column chromatography, the most readily adsorbed substances are retained near the top.

d. In column chromatography, the stationary phase is packed in a glass tube.


Select the correct statements.

1. a, c, d

2. a, b

3. b, c

4. a, b, c, d

Subtopic:  Refining Process |
 68%
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The chemical reactions taking place in the extraction of zinc from zinc blende is

1. 2ZnS+3O22ZnO + 2SO2

2. ZnO + C1673 KZn + CO

3. Both 1 and 2

4. None of the above

Subtopic:  Metallurgy of individual elements |
 83%
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The reaction that do not take place in the blast furnace during the extraction of iron is-

1. Fe2O3(s) + 3CO(g) → 2Fe3O4(s) + 3CO2(g)

2. FeO(s) + CO(g) → Fe(s) + CO2(g)

3. 2 C(s) + O2(g) → 2 CO(g)

4. None of the above

Subtopic:  Metallurgy of individual elements |
From NCERT
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