Class 12 Chemistry Chapter 6 General Principles and Processes of Isolation of Elements MCQs | Class 12 Chemistry Chapter 6 General Principles and Processes of Isolation of Elements Objective Type Questions and Answers

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Questions
1 Formula of copper pyrite is
A Cu2S
B CuFeS
C CuFeS2
D Cu2Fe2S2

Answer:CuFeS2
2 Ore of aluminium is
A bauxite
B hematite
C dolomite
D None of these

Answer:bauxite
3 Removal of the unwanted materials like sand, clays, etc. from the ore is known as ………., …….. or ……….
A concentration, dressing, benefaction
B separation, refining, gangue
C magnetic separation, purification, gangue
D washing, refining, amalgamation

Answer:concentration, dressing, benefaction
4 For which of the following ores froth floatation method is used for concentration?
A Haematite
B Zinc blende
C Magnetite
D Camallite

Answer:Zinc blende
5 The powdered ore is agitated with water or washed with running stream of water. The heavy ore particles and lighter impurities are separated. This method of concentration is known as
A metallurgy
B leaching
C froth floatation process
D gravity separation

Answer: gravity separation
6 The oil used as frothing agent in froth floatation process is
A coconut oil
B castor oil
C palmitic oil
D pine oil

Answer:pine oil
7 Sulphide ore of zinc/copper is concentrated by
A floatation process
B electromagnetic process
C gravity separation
D distillation

Answer:floatation process
8 Which of the following ores is concentrated by chemical leaching method?
A Cinnabar
B Argentite
C Copper pyrites
D Galena

Answer:Argentite
9 How do we separate two sulphide ores by froth floatation method?
A By using excess of pine oil
B By adjusting proportion of oil to water or using depressant
C By using some solvent in which one of the sulphides is soluble
D By using collectors and froth stabilisers like xanthates

Answer:By adjusting proportion of oil to water or using depressant
10 Common impurities present in bauxite are
A CuO
B ZnO
C CaO
D SiO2

Answer: SiO2
11 An ore of tin containing FeCrO4 is concentrated by
A gravity separation
B magnetic separation
C froth floatation
D leaching

Answer: magnetic separation
12 Which of the following ores cannot be concentrated by magnetic separation?
A Haematite
B Malachite
C Magnetite
D Siderite

Answer:Malachite
13 The significance of leaching in the extraction of aluminium is
A it helps removing the impurities like SiO2, Fe2O3 etc. from the bauxite ore
B it converts the ore into oxide
C it reduces melting point of the ore
D it eliminates water from bauxite

Answer: it helps removing the impurities like SiO2, Fe2O3 etc. from the bauxite ore
14 Which of the following metals is extracted using a silica lined convertor?
A Mg
B Al
C Cu
D Zn

Answer:Cu
15 Which of the following sulphides when heated strongly in air gives the corresponding metal without undergoing separate reduction of oxide?
A Cu2S
B FeS
C HgS
D ZnS

Answer:HgS
16 Which of the following metals cannot be obtained by reduction of its metal oxide bv aluminium ?
A Cr
B Mn
C Fe
D Mg

Answer: Mg
17 Heating pyrites to remove sulphur is called
A smelting
B calcination
C liquation
D roasting

Answer:roasting
18 Impurities of sulphur, silicon and phosphorus can be removed from cast iron by adding
A carbon which reduces the impurities
B water which dissolves the impurities
C limestone which changes impurities into oxides and pass into slag
D iron oxide which reacts with impurities by forming slag

Answer: limestone which changes impurities into oxides and pass into slag
19 In metallurgical process, aluminium acts as
A an oxidising agent
B a reducing agent
C acidic flux
D basic flux

Answer: a reducing agent
20 Ellingham diagram represents change of
A ΔG with temperature
B ΔH with temperature
C ΔG with pressure
D (ΔG – TΔS) with temperature

Answer:ΔG with temperature

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