General Principles of Isolation of Elements

The reaction that does NOT take place in blast furnace between 900 K to 1500 K temperature range during extraction of iron is :

1. FeO+CO Fe+CO2
2. C+CO2 2CO
3. CaO+SiO2 CaSiO3
4. Fe2O3+CO 2FeO+CO2

Which one of the following is not a calcination reaction?

1. CaCO3 + 2HCl CaCl2 + H2O + CO2
2. ZnCO3 ZnO + CO2
3. Fe2O3 . xH2O Fe2O3 + xH2O
4. CaCO3 . MgCO3 CaO + MgO + 2CO2

The maximum temperature that can be achieved in blast furnace is :

1. Upto 5000 K
2. Upto 1200 K
3. Upto 2200 K
4. Upto 1900 K

Which one of the following methods can be used to obtain highly pure metal which is liquid at room temperature?

1. Zone refining
2. Electrolysis
3. Chromatography
4. Distillation

Identify the correct statement from the following :

1. Blister copper has blistered appearance due to evolution of CO2
2. Vapour phase refining is carried out for Nickel by Van Arkel method.
3. Pig iron can be moulded into a variety of shapes.
4. Wrought iron is impure iron with 4\% carbon.

Which one is malachite from the following?

1. Fe3O4
2. CuCO3 Cu(OH)2
3. CuFeS2
4. Cu(OH)2

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

1. Fe
2. Zn
3. Mg
4. Cu

Extraction of gold and silver involves leaching with CN- ion. Silver is later recovered by

1. distillation
2. zone refining
3. displacement with Zn
4. liquation

In the extraction of copper from its sulphide ore, the metal is finally obtained by the reduction of cuprous oxide with

1. carbon monoxide
2. copper (I) sulphide
3. sulphur dioxide
4. iron (II) sulphide

"Metals are usually not found as nitrates in their ores." Out of the following two (I and II) reasons which is/are true for the above observation? I. Metal nitrates are highly unstable. II. Metal nitrates are highly soluble in water.

1. I is false but II is true.
2. I is true but II is false.
3. I and II are true.
4. I and II are false

The metal oxide which cannot be reduced to metal by carbon is

1. Al2O3
2. PbO
3. ZnO
4. Fe2O3

The Gibbs energy for the decomposition of Al2O3 at 500 is as follows 23Al2O3 43Al + O2 rG = +960 kJ mol-1 The potential difference needed for the electrolytic reduction of aluminium oxide (Al2O3) at 500 is at least

1. 4.5 V
2. 3.0 V
3. 2.5 V
4. 5.0 V

In the extraction of copper from its sulphide ore, the metal is finally obtained by the reduction of cuprous oxide with

1. carbon monoxide
2. copper (I) sulphide
3. sulphur dioxide
4. iron (II) sulphide.

Aluminium is extracted from alumina (Al2O3) by electrolysis of a molten mixture of

1. Al2O3 + HF + NaAlF4
2. Al2O3 + CaF2 + NaAlF4
3. Al2O3 + Na3AlF6 + CaF2
4. Al2O3 + KF + Na3AlF6

Which one of the following is a mineral of iron?

1. Malachite
2. Cassiterite
3. Pyrolusite
4. Magnetite

The following reactions take place in the blast furnace in the preparation of impure iron. Identify the reaction pertaining to the formation of the slag.

1. Fe2O3(s) + 3CO(g) 2Fe(l) + 3CO2(g)
2. CaCO3(s) CaO(s) + CO2(g)
3. CaO(s) + SiO2(s) CaSiO3(s)
4. 2C(s) + O2(g) 2CO(g)

Which of the following elements is present as the impurity to the maximum extent in pig iron?

1. Manganese
2. Carbon
3. Silicon
4. Phosphorus

Which of the following pairs of metals is purified by van Arkel method?

1. Ga and In
2. Zr and Ti
3. Ag and Au
4. Ni and Fe

Sulphide ores of metals are usually concentrated by froth flotation process. Which one of the following sulphide ores offers an exception and is concentrated by chemical leaching?

1. Galena
2. Copper pyrite
3. Sphalerite
4. Argentite

Which of the following statements about the advantage of roasting of sulphide ore before reduction is not true?

1. The fG of the sulphide is greater than those for CS2 and H2S.
2. The fG is negative for roasting of sulphide ore to oxide.
3. Roasting of the sulphide to the oxide is thermodynamically feasible.
4. Carbon and hydrogen are suitable reducing agents for metal sulphides.

The mass of carbon anode consumed (giving only carbon dioxide) in the production of 270 kg of aluminium metal from bauxite by the Hall process is (Atomic mass : Al = 27)

1. 270 kg
2. 540 kg
3. 90 kg
4. 180 kg

The method of zone refining of metals is based on the principle of

1. greater mobility of the pure metal than that of the impurity
2. higher melting point of the impurity than that of the pure metal
3. greater noble character of the solid metal than that of the impurity
4. greater solubility of the impurity in the molten state than in the solid