CBSE Class 12 Chemistry – MCQ and Online Tests – Unit 6 – general Principles and Processes of Isolation of Elements
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CBSE Class 12 Chemistry – MCQ and Online Tests – Unit 6 – Ggeneral Principles and Processes of Isolation of Elements
The oil used as frothing agent in froth floatation process is
(a) coconut oil
(b) castor oil
(c) palmitic oil
(d) pine oil
Answer: (d) pine oil
Which of the following metals is not extracted by leaching?
Answer: (b) Mercury
Sulphide ore of zinc/copper is concentrated by
(a) floatation process
(b) electromagnetic process
(c) gravity separation
Answer: (a) floatation process
Concentration of sulphide ore is done by
(a) froth flotation process
(d) None of these
Answer: (a) froth flotation process
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: (b) By adjusting proportion of oil to water or using depressant.
Which of the following ores is concentrated by chemical leaching method?
(c) Copper pyrites
Answer: (b) Argentite
Common impurities present in bauxite are
Answer: (d) SiO2
Which of the following ores cannot be concentrated by magnetic separation?
Answer: (b) Malachite
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: (a) it helps removing the impurities like SiO2, Fe2O3 etc. from the bauxite ore
Which of the following sulphides when heated strongly in air gives the corresponding metal without undergoing separate reduction of oxide?
Answer: (c) HgS
An ore of tin containing FeCrO4 is concentrated by
(a) gravity separation
(b) magnetic separation
(c) froth floatation
Answer: (b) magnetic separation
Heating pyrites to remove sulphur is called
Answer: (d) roasting
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: (c) limestone which changes impurities into oxides and pass into slag
Which of the following metals is extracted using a silica lined convertor?
Answer: (c) Cu
In metallurgical process, aluminium acts as
(a) an oxidising agent
(b) a reducing agent
(c) acidic flux
(d) basic flux
Answer: (b) a reducing agent
Malachite is an ore of
Answer: (b) copper
Ellingham diagram represents change of
(a) ΔG with temperature
(b) ΔH with temperature
(c) ΔG with pressure
(d) (ΔG – TΔS) with temperature
Answer: (a) ΔG with temperature
Which of the following metals cannot be obtained by reduction of its metal oxide bv aluminium ?
Answer: (d) Mg
For which of the following ores froth floatation method is used for concentration?
(b) Zinc blende
Answer: (b) Zinc blende
During the extraction of haematite, limestone is added which acts as
(c) reducing agent
Answer: (a) flux
In blast furnace iron oxide is reduced by
(b) carbon monoxide
(d) lime stone
Answer: (b) carbon monoxide
Which of the following oxides cannot be reduced by hydrogen?
(a) Ferric oxide
(b) Aluminium oxide
(c) Zinc oxide
(d) Cupric oxide
Answer: (b) Aluminium oxide
From the Ellingham graph between Gibb’s energy and temperature, out of C and CO with is a better reducing agent for ZnO?
(c) Both of these
(d) None of these
Answer: (a) Carbon
Formula of copper pyrite is
Answer: (c) CuFeS2
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: (a) concentration, dressing, benefaction
Ore of aluminium is
(d) None of these
Answer: (a) bauxite
In a thermite process is used as reducing agent.
Answer: (b) Al
Blister copper is
(a) impure copper
(b) obtained in self reduction process during bessermerisation
(c) Both are correct
(d) None is correct
Answer: (c) Both are correct
Which of the following slags is produced during extraction of iron?
Answer: (a) CaSiO3
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
(c) froth floatation process
(d) gravity separation
Answer: (d) gravity separation