CBSE Class 12 Chemistry General Principles and Processes of Isolation of Elements MCQs Set C

Question: The extraction of which of the following metals involves bessemerisation? 
(a) Fe
(b) Ag
(c) Al
(d) Cu 
Answer: d

 Question: In aluminothemuc process, Al is used as a/an 
(a) reducing agent
(b) oxidising agent
(c) catalyst
(d) electrolyte 
Answer: a

Question: Gold is extracted by hydrometallurgical process, based onits property 
(a) of being electropositive
(b) of being less reactive
(c) to form complexes which are water soluble
(d) to form salts which are water soluble 
Answer: c

Question: In metallurgical process, for which metal carbon is used for reduction of metal oxides? 
(a) Na
(b) Ag
(c) Fe
(d) Hg
Answer: c

Question: In the electrolytic method for obtaining aluminium from purified bauxite, cryolite is added to
(a) minimise the heat loss due to radiation 
(b) protect aluminium produced from oxygen
(c) dissolve bauxite and render it conductor of electricity
(d) lower the melting point of bauxite
Answer: d

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

Question: Aluminium is obtained by 
(a) reducing Al₂O₃ with coke
(b) electrolysing Al₂O₃ dissolved in Na₃ AIF₆
(c) reducing Al₂O₃ with chromium
(d) heating alumina with cryolite
Answer: b

Question: Argentite is an ore of
(a) Fe
(b) AI
(c) Cu
(d) Ag
Answer: d

Question: Calamine is
(a) CaCO₃
(b) MgCO₃
(c) ZnCO₃
(d) CaCO₃ + CaO
Answer: c

Question: Extraction of metal from the ore cassiterite involves
(a) carbon reduction of an oxide ore
(b) self-reduction of a sulphide ore
(c) removal of copper impurity
(d) removal of iron impurity
Answer: a,d

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

Question: In the electrolytic refining of zinc,
(a) graphite is at the anode
(b) the impure metal is at the cathode
(c) the metal ions get reduced at the anode
(d) acidified zinc sulphate is the electrolyte
Answer: d

Question: One of the following metals forms a volatile compound and this property is taken advantage for its extraction. This metal is
(a) iron
(b) nickel
(c) cobalt
(d) tungsten
Answer: b

Question: Aluminium metal is refined by 
(a) Serpeck’s process
(b) Baeyer’s process
(c) Hall’s process
(d) Hoope’s process
Answer: d

Question: Upon heating with Cu₂S, the reagent(s) that given copper metal is/are 
(a) CuFeS₂
(b) CuO
(c) Cu₂O
(d) CuSO₄
Answer: b,c,d

Question: On igniting Fe₂O₃ at 1400°C, the product obtained is
(a) Fe₂O₃ melt
(b) FeO 
(c) Fe₃O₄
(d) metallic iron
Answer: d

Question: Composition ofazmite mineral is
(a) CuCO₃ • CuO
(b) Cu(HCO₃)₂ · Cu(OH)₂
(c) 2CuCO₃ · Cu(OH)₂
(d) CuCO₃ · 2 Cu(OH)₂
Answer: c

Question: Bauxite ore is made up of Al₂O₃ + SiO₂ + TiO₂ + Fe₂O₃ . This ore is treated with cone. Na OH solution at 500 Kand 35 bar pressure for few hours and filtered hot. In the filtrate, the species present are 
(a) NaAl(OH)₄
(b) Na₂Ti(OH)₆
(c) Na[Al(OH)₄ ] and Na₂SiO₃
(d) Na₂SiO₃ 
Answer: c

Question: Cyanide process is used for extraction of
(a) Ag
(b) Ni
(c) Pt
(d) Zn
Answer: a

Question: During the process of electrolytic refining of copper, some metals present as impurity settle as ‘anode mud’. These are 
(a) Fe and Ni
(b) Ag and Au
(c) Pb and Zn
(d) Se and Ag
Answer: b

Question: Identify the reaction that does not take place in a blast furnace. 
(a) CaCO₃ → CaO + CO₂
(b) CaO + SiO₂ → CaSiO₃
(c) 2Fe₂O₃ + 3C → 4Fe + 3CO₂
(d) CO₂ + C → 2CO
Answer: c

Question: Which of the following is true for electrolytic refining?
(a) Pure metal is anode and impure metal is cathode
(b) Pure metal is cathode and impure metal is anode
(c) Both are anode
(d) Both are cathode 
Answer: b

Question: Which one of the following ores is an ore of copper?
(a) Argentite
(b) Haematite 
(c) Malachite
(d) Calamine
Answer: c

Question: The temperature of the slag zone in the metallurgy of iron using blast furnace is
(a) 1200- 1500°C
(b) 1500-1600°C
(c) 400-700°C
(d) 800-1000°C
Answer: d

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

Question: Metallic silver may be obtained from AgCl by
(a) heating it in the current of H₂ 
(b) fusing it with sand
(c) treating with carbon monoxide
(d) fusing it with Na₂CO₃
Answer: d

Question: Gravity separation process is used for the concentration of 
(a) calamine
(b) haematite
(c) chalcopyrite
(d) bauxite
Answer: b

Question: In Mac Arthm Forrest method, silver is extracted from the solution of Na [Ag(CN)₂ ] by the use of 
(a) Fe
(b) Mg
(c) Cu
(d) Zn
Answer: d

Question: Siderite is an ore of 
(a) Cu
(b) Al
(c) Ag
(d) Fe
Answer: d

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

Question: Carbon cannot be used in the reduction of Al₂O₃ because 
(a) it is an expensive proposition 
(b) the enthalpy of formation of CO₂ is more than that of Al₂O₃
(c) pure carbon is not easily available
(d) the enthalpy of formation of Al₂O₃ is too high
Answer: d

Question: Which one of the following metals is extracted by a carbon reduction process? 
(a) Copper
(b) Iron
(c) Aluminium
(d) Magnesium
Answer: b

Question: Blister copper is
(a) impure Cu
(b) Cu alloy
(c) pure Cu
(d) Cu having 1% impurities
Answer: d

Question: In blast furnace, iron oxide is reduced by
(a) hot blast of air
(b) carbon monoxide
(c) carbon
(d) silica
Answer: b

Question: In electrorefining of copper, some gold is deposited as
(a) cathode
(b) e lectrode
(c) cathode mud
(d) anode mud
Answer: d

Question: In the extraction of Fe from Fe₂O₃ , the reducing agent used is
(a) C
(c) electrolytic reduction
(b) Al
(d) Cu
Answer: a

Question: Identify the ore not containing iron. 
(a) Limonite
(b) Siderite
(c) Carnallite
(d) Chalcopyrites
Answer: c

Question: Which one of the following is the chief ore of copper?
(a) Galena
(c) Sphalerite
(b) Copper pyrites
(d) Siderite
Answer: b

Question: When copper pyrites is roasted in excess of air, a mixture of CuO + FeO is formed. FeO is present as impurities. This can be removed as slag during reduction of CuO. The flux added to form slag is 
(a) SiO₂ , which is an acidic flux
(b) limestone, which is a basic flux
(c) SiO₂ , which is a basic flux
(d) Cao, which is a basic flux
Answer: a

Question: Heating mixture of Cu₂O and Cu₂ Swill give
(a) Cu₂ SO₃
(b) CuO + CuS
(c) Cu+ SO₃
(d) Cu+ SO₂
Answer: d

Question: Identify the reaction that does not take place during the smelting process of extraction. 
(a) 2FeS + 3 O₂ → 2 FeO + 2 SO₂ ↑
(b) Cu₂O + FeS → Cu₂S + FeO
(c) 2 Cu₂S + 3 O₂ → 2 Cu₂O + 2 SO₂ ↑
(d) FeO+ SiO₂ → FeSiO₃
Answer: a

Question: From the Ellingham graph on carbon, which of the following statements is false? 
(a) CO reduces Fe₂O₃ to Fe at less than 983 K
(b) CO is less stable than CO₂ at more than 983 K
(c) CO reduces Fe₂O₃ to Fe in the reduction zone of blast furnace
(d) CO₂ is more stable than CO at less than 983 K
Answer: b

Question: During the extraction of gold, the following reactions take place
Au+ CN^– + H₂O →^O₂ X
X + Zn → Y + Au
X and Y respectively, are
(a) [Au (CN)₂ r and [Zn (CN)₆ J^4-
(b) [Au (CN)₄]^2- and [Zn (CN)₄]^2-
(c) [Au (CN)₄]^3- and [Zn (CN)₄]^2-
(d) [Au (CN)₂]^–and [Zn(CN)₄]^2-
Answer: d

Question: Observe the following statements regarding purification of bauxite.
I. During Hall’s process, silica is removed as Si (vapour).
II. Bauxite ore contaminated with FeiO₃ is purified in Baeyer’s process.
III. During Serpeck’s process, AIN is formed. The correct answer is
(a) I, II and III
(b) I and II
(c) I and III
(d) II and III
Answer: d