Worksheets Chapter 6 General Principles and Processes of Isolation of Elements Class 12 Chemistry

Students should refer to Worksheets Class 12 Chemistry General Principles and Processes of Isolation of Elements Chapter 6 provided below with important questions and answers. These important questions with solutions for Chapter 6 General Principles and Processes of Isolation of Elements have been prepared by expert teachers for Class 12 Chemistry based on the expected pattern of questions in the Class 12 exams. We have provided Worksheets for Class 12 Chemistry for all chapters on our website. You should carefully learn all the important examinations questions provided below as they will help you to get better marks in your class tests and exams.

General Principles and Processes of Isolation of Elements Worksheets Class 12 Chemistry

GENERAL PRINCIPLES AND PROCESSES OF ISOLATION OF ELEMENTS

Question. Which of the following condition favours the reduction of a metal oxide to metal?
(a) ΔH = +ve, TΔS = + ve at low temperature
(b) ΔH = +ve, TΔS = – ve at any temperature
(c) ΔH = –ve, TΔS = – ve at high temperature
(d) ΔH = –ve, TΔS = + ve at any temperature

Question. Function of the flux added during smelting is
(a) to make ore porous
(b) to remove gangue
(c) to make reduction easier
(d) to precipitate slag

Question. Which of the following metal is used in the manufacture of dye-stuffs and paints ?
(a) Copper
(b) Zinc
(c) Aluminium
(d) Magnesium

Question. Furnaces are lined with calcium oxide because
(a) it gives off oxygen on heating
(b) it gives strong light on heating
(c) it is refractory and basic
(d) it is not affected by acids

Question. An example of an oxide ore is
(a) Bauxite
(b) Malachite
(c) Zinc blende
(d) Feldspar

Question. 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.
(a) Fe₂O₃(s) + 3 CO(g) → 2 Fe (l) + 3 CO₂ (g)
(b) CaCO₃ (s) → CaO (s) + CO₂ (g)
(c) CaO (s) + SiO₂(s) → CaSiO₃(s)
(d) 2C(s) + O₂ (g) → 2 CO(g)

Question. Refractory materials are generally used in furnaces because
(a) they possess great structural strength
(b) they can withstand high temperature
(c) they are chemically inert
(d) they do not require replacement

Question. Galena is an ore of
(a) Pb
(b) Hg
(c) Zn
(d) None of these

Question. Cast iron is
(a) made by melting pig iron with scrap iron and coke using hot air blast
(b) having slightly lower carbon content (about 3%) as compared to pig iron
(c) extremely hard and brittle
(d) All of the above statements are true

Question. In the extraction of Cu, the metal is formed in the bessemer converter due to the reaction :
(a) Cu₂S + 2Cu₂O → 6Cu + SO₂
(b) Cu₂S → 2Cu + S
(c) Fe + Cu₂O → 2Cu + FeO
(d) 2Cu₂O → 4Cu + O₂

Question. Roasting is generally done in case of the
(a) oxide ores
(b) silicate ores
(c) sulphide ores
(d) carbonate ores

Question. Electrometallurgical process is used to extract
(a) Fe
(b) Pb
(c) Na
(d) Ag

Question. Which one of the following is an ore of silver ?
(a) Argentite
(b) Stibnite
(c) Haematite
(d) Bauxite

Question. Aluminothermic process is used for the extraction of metals,whose oxides are
(a) fusible
(b) not easily reduced by carbon
(c) not easily reduced by hydrogen
(d) strongly basic

Question. Cinnabar is an ore of
(a) Hg
(b) Cu
(c) Pb
(d) Zn

Question. The electrolytic method of reduction is employed for the preparation of metals that
(a) are weakly electropositive
(b) are moderately electropositive
(c) are strongly electropositive
(d) form oxides

Question. The method of concentrating the ore which makes use of the difference in density between ore and impurities is called
(a) levigation
(b) leaching
(c) magnetic separation
(d) liquifaction

Question. In the extraction of aluminium by Hall-Heroult process, purified Al₂O₃ is mixed with CaF₂ to
(i) lower the melting point of Al₂O₃.
(ii) increase the conductivity of molten mixture.
(iii) reduce Al³⁺ into Al(s).
(iv) acts as catalyst.
(a) (i) and (ii)
(b) (i), (ii) and (iii)
(c) (iii) and (iv)
(d) (ii), (iii) and (iv)

Question. In the extraction of chlorine by electrolysis of brine______.
(a) oxidation of Cl– ion to chlorine gas occurs.
(b) reduction of Cl– ion to chlorine gas occurs.
(c) For overall reaction ΔG has negative value.
(d) a displacement reaction takes place.

Question. Blister copper is
(a) Impure Cu
(b) Cu alloy
(c) Pure Cu
(d) Cu having 1% impurity

Question. The metal always found in the free states is
(a) Au
(b) Ag
(c) Cu
(d) Na

Question. Which form of the iron contains 4% carbon ?
(a) Cast iron
(b) Pig iron
(c) Wrought iron
(d) Both (a) and (b)

Question. Which of the following reaction takes place in blast furnace during extraction of copper ?
(a) 2Cu₂S + 3O₂ → 2Cu₂O + 2SO₂
(b) 2FeS + 3O₂ → 2FeO + 2SO₂
(c) 2Cu₂O + Cu₂S → 6Cu +SO₂
(d) All of these

Question. In the extraction of copper from its sulphide ore, the metal is finally obtained by the reduction of cuprous oxide with :
(a) Copper (I) sulphide (Cu₂S)
(b) Sulphur dioxide (SO₂)
(c) Iron sulphide (FeS)
(d) Carbon monoxide (CO)

Question. The process of zone refining is used in the purification of
(a) Si
(b) Al
(c) Ag
(d) Cu

Question. Which of the following pair is incorrectly matched ?
(a) Magnetite – Fe₃O₄
(b) Copper glance – Cu₂S
(c) Calamine – ZnCO₃
(d) Zincite – ZnS

Question. Which one of the following ores is best concentrated by froth-flotation method ?
(a) Galena
(b) Cassiterite
(c) Magnetite
(d) Malachite

Question. The method not used in metallurgy to refine the impure metal is
(a) Mond’s process
(b) Van–Arkel process
(c) Amalgamation process
(d) Liquation

Question. All ores are minerals, while all minerals are not ores because
(a) the metal can’t be extracted economically from all the minerals
(b) minerals are complex compounds
(c) the minerals are obtained from mines
(d) all of these are correct

Question. Which one of the following is not a sulphide ore?
(a) Magnetite
(b) Iron pyrites
(c) Copper glance
(d) Sphalerite

Question. Which of the following pairs of metals is purified by van Arkel method ?
(a) Ga and In
(b) Zr and Ti
(c) Ag and Au
(d) Ni and Fe

Question. Aluminium is extracted from alumina (Al₂O₃ ) by electrolysis of a molten mixture of
(a) Al₂O₃ + HF + NaAlF₄
(b) Al₂O₃ + CaF₂ + NaAlF₄
(c) Al₂O₃ + Na₃AlF₆ + CaF₂
(d) Al₂O₃ + KF + Na₃AlF₆

Question. The method of zone refining of metals is based on the principle of
(a) greater solubility of the impurities in the molten state than in the solid
(b) greater mobility of the pure metal than that of the impurite
(c) higher melting point of the impurities than that of the pure metal
(d) greater noble character of the solid metal than that of the impurities

Question. The process of zone refining is used in the purification of
(a) Si
(b) Al
(c) Ag
(d) Cu

Question. Extraction of zinc from zinc blende is achieved by
(a) electrolytic reduction
(b) roasting followed by reduction with carbon
(c) roasting followed by reduction with another metal
(d) roasting followed by self-reduction

MATCHING TYPE QUESTIONS 

Question. Match the columns
Column-I                                        Column-II
(A) This metal is used in                (p) Zinc
extraction of chromium
and manganese.
(B) Common metal in brass           (q) Aluminium
and bronze.
(C) Common metal in brass            (r) Copper
and german silver.
(D) Substance used in making        (s) Stainless steel
cycles, automobiles,
utensils, etc.
(a) A – (q), B – (r), C – (p), D – (s)
(b) A – (r), B – (q), C – (p), D – (s)
(c) A – (q), B – (p), C – (r), D – (s)
(d) A – (q), B – (r), C – (s), D – (p)

Question. Match the columns
Column-I                                Column-II
(A) Cyanide process                 (p) Ultrapure Ge
(B) Floatation process              (q) Pine oil
(C) Electrolytic reduction          (r) Extraction of Al
(D) Zone refining                     (s) Extraction of Au
(a) A – (r), B – (p), C – (s), D – (q)
(b) A – (s), B – (q), C – (r), D – (p)
(c) A – (r), B – (q), C – (s), D – (p)
(d) A – (s), B – (p), C – (r), D – (q)

Question. Match the columns
Column – I                                       Column – II
(A) According to Δ_rG^Θ vsT               (p) Sulphur oxide
graph, oxide of this metal
can be easily reduced to
corresponding metal by
heating with coke
(B) Substance responsible for          (q) Copper
the blistered appearence
of the copper obtained as
result of extraction of
copper from cuprous oxide
(C) Metal which during                   (r) Na₃AlF₆ or CaF₂
purification is distilled
off and collected by
rapid chilling
(D) On addition to Al₂O₃ its            (s) Zinc
melting point gets reduced
and conductivity gets
enhanced
(a) A – (p), B – (q), C – (s), D – (r)
(b) A – (q), B – (s), C – (p), D – (r)
(c) A – (q), B – (p), C – (s), D – (r)
(d) A – (q), B – (p), C – (r), D – (s)

Question. Match the columns
Column-I                            Column-II
(A) Distillation                      (p) Zr
(B) Electrolytic refining          (q) Ga
(C) Liquation                        (r) Cu
(D) Zone refining                  (s) Hg
(E) Vapour phase refining      (t) Sn
(a) A – (r), B – (s), C – (t), D – (q), E – (p)
(b) A – (s), B – (r), C – (t), D – (q), E – (p)
(c) A – (s), B – (t), C – (r), D – (q), E – (p)
(d) A – (s), B – (r), C – (p), D – (q), E – (t)

Question. Match the columns.
Column-I                                     Column-II
(A) Cyanide process                   (p) Ultrapure Ge
(B) Froth Floatation Process       (q) Dressing of ZnS
(C) Electrolytic reduction           (r) Extraction of Al
(D) Zone refining                      (s) Extraction of Au
(t) Purification of Ni
(a) A – (s), B – (q), C – (r), D – (p)
(b) A – (q), B – (r), C – (p), D – (t)
(c) A – (p), B – (q), C – (r), D – (s)
(d) A – (r), B – (s), C – (t), D – (p)

CRITICAL THINKING TYPE QUESTIONS

Question. Which one of the following does not occur as sulphide ore?
(a) Zn
(b) Cr
(c) Ag
(d) Fe

Question. Pyrolusite is a/an
(a) oxide ore
(b) sulphide ore
(c) carbide ore
(d) Not an ore

Question. Sulphide ores of metals are usually concentrated by froth flotation process. Which one of the following sulphide ores offer an exception and is concentrated by chemical leaching?
(a) Galena
(b) Copper pyrite
(c) Sphalerite
(d) Argentite

Question. Which of the following statements is correct ?
(a) Gangues are carefully chosen to combine with the slag present in the ore to produce easily fusible flux to carry away the impurities
(b) Slags are carefully chosen to combine with the flux present in the ore to produce easily fusible gangue to carry away the impurities
(c) Gangues are carefully chosen to combine with the flux present in the ore to produce easily fusible slag to carry away the impurities
(d) Fluxes are carefully chosen to combine with the gangue present in the ore to produce easily fusible slag to carry away the impurities 

Question. In the cyanide extraction process of silver from argentite ore, the oxidising and reducing agents used are
(a) O₂ and CO respectively
(b) O₂ and Zn dust respectively
(c) HNO₃ and Zn dust respectively
(d) HNO₃ and CO respectively 

Question. Which ore contains both iron and copper?
(a) Cuprite
(b) Chalcocite
(c) Chalcopyrite
(d) Malachite

Question. Extraction of which of the following is based on oxidation ?
(a) Highly reactive metals
(b) Moderately reactive metals
(c) Non-metals
(d) Both (a) and (c)

Question. The temperature in °C at which Fe₂O₃ is finally reduced to Fe in the blast furnace is
(a) 993
(b) 797
(c) 897
(d) 1597

Question. Which of the following statements, about the advantage of roasting of sulphide ore before reduction is not true?
(a) The of ΔG⁰_f of the sulphide is greater than those for CS₂ and H₂S.
(b) The of ΔG⁰_f is negative for roasting of sulphide ore to oxide.
(c) Roasting of the sulphide to the oxide is thermodynamically feasible.
(d) Carbon and hydrogen are suitable reducing agents for reduction of metal sulphides.

Question. Cu₂S + 2Cu₂O → 6Cu +SO₂
In which process of metallurgy of copper, above equation is involved?
(a) Roasting
(b) Self reduction
(c) Refining
(d) Purification

Question. Before introducing FeO in blast furnace , it is converted to Fe₂O₃ by roasting so that
(a) it may not be removed as slag with silica
(b) it may not evaporate in the furnace
(c) presence of it may increase the m.pt. of charge
(d) None of these. 

Question. Which of the following reaction(s) occur in temperature range 500 – 800 K in blast furnace.
(i) Fe₂O₃ + CO → 2FeO +CO₂
(ii) Fe₃O₄ + 4CO → 3Fe + 4CO₂
(iii) FeO+ CO → Fe + CO₂
(iv) C + CO₂ → 2CO
(a) (i) and (ii)
(b) (i), (ii) and (iii)
(c) (iii) and (iv)
(d) (iv) only

Question. When copper ore is mixed with silica, in a reverberatory furnace copper matte is produce d. The copper matte contains________.
(a) sulphides of copper (II) and iron (II)
(b) sulphides of copper (II) and iron (III)
(c) sulphides of copper (I) and iron (II)
(d) sulphides of copper (I) and iron (III)