CBSE Class 12 Chemistry – MCQ and Online Tests – Unit 6 – general Principles and Processes of Isolation of Elements
Every year CBSE conducts board exams for 12th standard. These exams are very competitive to all the students. So our website provides online tests for all the 12th subjects. These tests are also very effective and useful for those who preparing for competitive exams like NEET, JEE, CA etc. It can boost their preparation level and confidence level by attempting these chapter wise online tests.
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CBSE Class 12 Chemistry – MCQ and Online Tests – Unit 6 – Ggeneral Principles and Processes of Isolation of Elements
Question 1.
The oil used as frothing agent in froth floatation process is
(a) coconut oil
(b) castor oil
(c) palmitic oil
(d) pine oil
Answer
Answer: (d) pine oil
Question 2.
Which of the following metals is not extracted by leaching?
(a) Aluminium
(b) Mercury
(c) Silver
(d) Gold
Answer
Answer: (b) Mercury
Question 3.
Sulphide ore of zinc/copper is concentrated by
(a) floatation process
(b) electromagnetic process
(c) gravity separation
(d) distillation
Answer
Answer: (a) floatation process
Question 4.
Concentration of sulphide ore is done by
(a) froth flotation process
(b) electrolysis
(c) roasting
(d) None of these
Answer
Answer: (a) froth flotation process
Question 5.
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
Answer: (b) By adjusting proportion of oil to water or using depressant.
Question 6.
Which of the following ores is concentrated by chemical leaching method?
(a) Cinnabar
(b) Argentite
(c) Copper pyrites
(d) Galena
Answer
Answer: (b) Argentite
Question 7.
Common impurities present in bauxite are
(a) CuO
(b) ZnO
(c) CaO
(d) SiO2
Answer
Answer: (d) SiO2
Question 8.
Which of the following ores cannot be concentrated by magnetic separation?
(a) Haematite
(b) Malachite
(c) Magnetite
(d) Siderite
Answer
Answer: (b) Malachite
Question 9.
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
Answer: (a) it helps removing the impurities like SiO2, Fe2O3 etc. from the bauxite ore
Question 10.
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
Answer: (c) HgS
Question 11.
An ore of tin containing FeCrO4 is concentrated by
(a) gravity separation
(b) magnetic separation
(c) froth floatation
(d) leaching
Answer
Answer: (b) magnetic separation
Question 12.
Heating pyrites to remove sulphur is called
(a) smelting
(b) calcination
(c) liquation
(d) roasting
Answer
Answer: (d) roasting
Question 13.
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
Answer: (c) limestone which changes impurities into oxides and pass into slag
Question 14.
Which of the following metals is extracted using a silica lined convertor?
(a) Mg
(b) Al
(c) Cu
(d) Zn
Answer
Answer: (c) Cu
Question 15.
In metallurgical process, aluminium acts as
(a) an oxidising agent
(b) a reducing agent
(c) acidic flux
(d) basic flux
Answer
Answer: (b) a reducing agent
Question 16.
Malachite is an ore of
(a) iron
(b) copper
(c) zinc
(d) Sliver
Answer
Answer: (b) copper
Question 17.
Ellingham diagram represents change of
(a) ΔG with temperature
(b) ΔH with temperature
(c) ΔG with pressure
(d) (ΔG – TΔS) with temperature
Answer
Answer: (a) ΔG with temperature
Question 18.
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
Answer: (d) Mg
Question 19.
For which of the following ores froth floatation method is used for concentration?
(a) Haematite
(b) Zinc blende
(c) Magnetite
(d) Camallite
Answer
Answer: (b) Zinc blende
Question 20.
During the extraction of haematite, limestone is added which acts as
(a) flux
(b) slag
(c) reducing agent
(d) gangue
Answer
Answer: (a) flux
Question 21.
In blast furnace iron oxide is reduced by
(a) silica
(b) carbon monoxide
(c) carbon
(d) lime stone
Answer
Answer: (b) carbon monoxide
Question 22.
Which of the following oxides cannot be reduced by hydrogen?
(a) Ferric oxide
(b) Aluminium oxide
(c) Zinc oxide
(d) Cupric oxide
Answer
Answer: (b) Aluminium oxide
Question 23.
From the Ellingham graph between Gibb’s energy and temperature, out of C and CO with is a better reducing agent for ZnO?
(a) Carbon
(b) CO
(c) Both of these
(d) None of these
Answer
Answer: (a) Carbon
Question 24.
Formula of copper pyrite is
(a)Cu2S
(b) CuFeS
(c) CuFeS2
(d) Cu2Fe2S2
Answer
Answer: (c) CuFeS2
Question 25.
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
Answer: (a) concentration, dressing, benefaction
Question 26.
Ore of aluminium is
(a) bauxite
(b) hematite
(c) dolomite
(d) None of these
Answer
Answer: (a) bauxite
Question 27.
In a thermite process is used as reducing agent.
(a) Zn
(b) Al
(c) Mn
(d) Fe
Answer
Answer: (b) Al
Question 28.
Blister copper is
(a) impure copper
(b) obtained in self reduction process during bessermerisation
(c) Both are correct
(d) None is correct
Answer
Answer: (c) Both are correct
Question 29.
Which of the following slags is produced during extraction of iron?
(a) CaSiO3
(b) FeSiO3
(c) MgSiO3
(d) ZnSiO3
Answer
Answer: (a) CaSiO3
Question 30.
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
Answer: (d) gravity separation
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