Bihar Board 12th Chemistry Objective Answers Chapter 6 General Principles and Processes of Isolation of Elements

Bihar Board 12th Chemistry Objective Questions and Answers

Bihar Board 12th Chemistry Objective Answers Chapter 6 General Principles and Processes of Isolation of Elements

Question 1.
Which of the following example is not correctly matched ?
(a) Two most abudant elements-Fe, Al
(b) Two metals which occur in native state-Au, Pt
(c) Two metals which can occur in combined and native state both-Zn,Fe.
(d) None of these
Answer:
(c) Two metals which can occur in combined and native state both-Zn,Fe.

Question 2.
Which of the following is not the correct name of the formula of the ore given with it ?
(a) MgSO₄.7H₂O – Epsom salt
(b) CuCO₃.Cu(OH)₂ – Malachite
(c) KAlSi₃O₈-Feldspar
(d) MgCl₂.6H₂O – Dolomite
Answer:
(d) MgCl₂.6H₂O – Dolomite

Question 3.
In which of the following the name of the ore is not matched with its formula ?
(a) Cassiterite – SnO₂
(b) Limonite – FeCO₃ . 3H₂O
(c) Siderite – FeCO₃
(d) Anglesite – PbCO₃
Answer:
(d) Anglesite – PbCO₃

Question 4.
Pyrolusite is …..
(a) a suiphide ore of Mn
(b) an oxide ore of Mn
(c) a carbide ore of P
(d) a chloride ore of Zn
Answer:
(d) a chloride ore of Zn

Question 5.
The name of the metal which is extracted from the ore is given below. Mark the example which is not correct.
(a) Malachite – Cu
(b) Calamine – Zn
(c) Chromite – Cr
(d) Dolomite – Al
Answer:
(d) Dolomite – Al

Question 6.
Which of the followings is magnetite ?
(a) Fe₂CO₃
(b) Fe₂O₃
(c) Fe₃O₄
(d) Fe₂O₃.3H₂O
Answer:
(c) Fe₃O₄

Question 7.
Which of the following is not an ore of magnesium ?
(a) Camallite
(b) Magnesite
(c) Dolomite
(d) Gypsum
Answer:
(d) Gypsum

Question 8.
Which of the following is not an oxide ore ?
(a) Corundum
(b) Zincite
(c) Calamine
(d) Chromite
Answer:
(c) Calamine

Question 9.
Which one of the following is not a sulphide ore ?
(a) Galena
(b) Iron pyrites
(c) Magnetite
(d) Copper glance
Answer:
(c) Magnetite

Question 10.
Which of the following is a halide ore ?
(a) Cassiterite
(b) Anglesite
(c) Siderite
(d) Camallite
Answer:
(d) Camallite

Question 11.
Which of the following is not a carbonate ore ?
(a) Dolomite
(b) Calamine
(c) Siderite
(d) Zincite
Answer:
(d) Zincite

Question 12.
Find the incorrect match.
(a) Kaolinite – [Al₂(OH)₄ Si₂O₅]
(b) Siderite – Fe₂O₃
(c) Sphalerite – Zns
(d) Magnetite – Fe₃O₄
Answer:
(b) Siderite – Fe₂O₃

Question 13.
Which of the following ores cannot be concentrated by magnetic spearation ?
(a) Haematite
(b) Malachite
(c) Magnetite
(d) Siderite
Answer:
(b) Malachite

Question 14.
An ore of tin containing, FeCr0₄ is concentrated by
(a) gravity separation
(b) magnetic separation
(c) froth floatation
(d) leaching
Answer:
(b) magnetic separation

Question 15.
Sulphide ore of zinc/copper is concentrated by
(a) floatation process
(b) electromagnetic proess
(c) gravity separation
(d) distillation
Answer:
(a) floatation process

Question 16.
For which of the following ores froth floatation method is used for concentration ?
(a) Haematite
(b) Zinc blende
(c) Magnetite
(d) Camallite
Answer:
(b) Zinc blende

Question 17.
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

Question 18.
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 collectors and froth stabilisers like xanthates
(d) By using some solvent in which one of the sulphides is soluble
Answer:
(b) By adjusting proportion of oil to water or using depressant

Question 19.
Common impurities present in bauxite are
(a) CuO
(b) ZnO
(c) CaO
(d) SrO₂
Answer:
(d) SrO₂

Question 20.
Which of the following reactions does not take place during leaching for concentration of bauxite ?
(a) Al₂O₃ + 2NaOH + 3H₂O → 2Na[Al(OH)₄]
(b) 2Na[Al(OH)₄]+CO₂ → Al₂O₃.xH₂O + 2NaHCO₃

Answer:
(c) Al₂O₃.2H₂O → Al₂O₃ + 2H₂O

Question 21.
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 melthing 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

Question 22.
Which of the following metals is not extracted by leaching ?
(a) Aluminium
(b) Mercury
(c) Silver
(d) Gold
Answer:
(b) Mercury

Question 23.
Heating pyrites to remove sulphur is called ……………….
(a) smelting
(b) calcination
(c) liquation
(d) roasting
Answer:
(d) roasting

Question 24.
Which of the following is not an example of roasting ?
(a) 2ZnS + 3O₂ → 2ZnO + 2SO₂
(b) 2PbS + 3O₂ → 2PbO + 2SO₂
(c) 2Cu → S + 3O₂ → 2Cu₂O + 2SO₂
(d) 2Cu₂O + Cu₂S → 6Cu + SO₂
Answer:
(d) 2Cu₂O + Cu₂S → 6Cu + SO₂

Question 25.
Which of the following metals is extracted using a silica lined convertor ?
(a) Mg
(b) Al
(c) Cu
(d) Zn
Answer:
(c) Cu

Question 26.
Which of the following reactions show the process of smelting ?
(a) 2PbO + PbS → 3Pb + SO₂
(b) 2Na[Au(CN)₂] + Zn → Na₂[Zn(CN)₄] + 2Au
(c) PbO + CPb + CO
(d) 2HgS + 3O₂ → 2HgO + 2SO₂
Answer:
(c) PbO + CPb + CO

Question 27.
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:
(c) HgS

Question 28.
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

Question 29.
Which of the following reactions takes place at higher temperature range (900 K-1500 K) in blast furnace ?
(a) 3Fe₂O₃ + PCO → 2Fe₃+CO₂
(b) FeO + CO → Fe + CO₂
(c) Fe₃O₄ +4CO → 3Fe + 4CO₂
(d) Fe₂O₃ + CO → 2FeO + CO₂
Answer:
(a) 3Fe₂O₃ + PCO → 2Fe₃+CO₂

Question 30.
During the extraction of heematite, limestone is added which acts as
(a) flux
(b) slag
(c) reducing agent
(d) gangue
Answer:
(a) flux

Question 31.
Which of the following stage is produced during extraction of iron ?
(a) CaSiO₃
(b) FeSiO₃
(c) MgSiO₃
(d)ZnSiO₃
Answer:
(a) CaSiO₃

Question 32.
Wrought iron is manufactured from cast iron by heathing it with
(a) C
(b) CaCO₃
(c) Fe₂O₃
(d) SiO₂
Answer:
(c) Fe₂O₃

Question 33.
In blast furnace iron oxide is reduced by
(a) silica
(b) carbon monoxide
(c) carbon
(d) lime stone
Answer:
(b) carbon monoxide

Question 34.
Blister copper is …………..
(a) impure copper
(b) obtained in self-reduction process during bessemerisation
(c) Both are correct
(d) None is correct
Answer:
(c) Both are correct

Question 35.
From the Ellingham graph between Gibb’s energy and temperature, out of C and CO which is a better reducing agent for ZnO ?
(a) Carbon
(b) CO
(c) Both of these
(d) None of these
Answer:
(a) Carbon

Question 36.
In a thermite process………. is used as reducing agent.
(a) Zn
(b) Al
(c) Mn
(d) Fe
Answer:
(b) Al

Question 37.
In metallurgical process, aluminium acts as …………………
(a) an oxidising agent
(b) basic flux
(c) acidic flux
(d) basic flux
Answer:
(b) basic flux

Question 38.
Which of the following metals cannot be obtained by reduction of its metal oxide by aluminium ?
(a) Cr
(b) Mn
(c) Fe                   ’
(d) Mg
Answer:
(d) Mg

Question 39.
Which of the following metals is obtained by electrolytic reduction process ?
(a) Fe
(b) Cu
(c) Ag
(d) Al
Answer:
(d) Al

Question 40.
Cryolite and fluorspar are mixed with Al₂O₃ during ‘ electrolysis for extraction of aluminium to
(a) increases the mass of the reaction mixture
(b) get other products at anode like fluorine
(c) lower the melting point and increase the conductivity of the electrolyte
(d) reduce aluminium oxide by cryolite
Answer:
(c) lower the melting point and increase the conductivity of the electrolyte

Question 41.
Which of the following metals cannot be obtained by electrolysis ?
(a) Cr
(b) Na
(c) Ca
(d) Mg
Answer:
(a) Cr

Question 42.
Extraction of chlorine from brine is based on
(a) reduction
(b) displacement
(c) oxidation
(d) evaporation
Answer:
(c) oxidation

Question 43.
…. being highly reactive is used in the extraction of chromium and manganese.
(a) Al
(b) Zn
(c) Cu
(d) Mg
Answer:
(a) Al

Question 44.
Which of the following is not a method of refining of metals ?
(a) Electrolysis
(b) Semlting
(c) Poling
(d) Liquation
Answer:
(b) Semlting

Question 45.
Most electropositive metals are obtained from their ores by ………….
(a) autoreduction
(b) smelting with carbon
(c) electrolysis of fused salts
(d) thermal decomposition
Answer:
(c) electrolysis of fused salts

Question 46.
Which one of the following is true in electrolytic refining ?
(a) Impure metal is made cathode
(b) Impure metal is made anode
(c) Impure metal is made cathode and pure metal as anode
(d) Both electrodes must be of pure metal
Answer:
(b) Impure metal is made anode

Question 47.
Carnallite on electrolysis gives ………..
(a) Mg and CI₂
(b) Ca and Cl₂
(c) K and Cl₂
(d) Al and Cl₂
Answer:
(c) K and Cl₂

Question 48.
In electro-refining of copper, some gold is deposited as
(a) cathode mud
(b) electrolyte
(c) anode mud
(d) cathode
Answer:
(c) anode mud

Question 49.
During the process of electrolytic refining of copper, some metals present as impurity settle as ‘anode mud’. These are
(a) Sn and Ag
(b) Pb and Zn
(c) Ag and Au
(d) Fe and Ni
Answer:
(c) Ag and Au

Question 50.
Which of the following is used as a method of purification for silicon ?
(a) Electrolytic refining
(b) Liquation
(c) Zone refining
(d) Distillation
Answer:
(c) Zone refining

Question 51.
Impure

The above process of purification of the metal is known as
(a) van Arkel process
(b) pyrometallurgy
(c) Mond process
(d) zone refining
Answer:
(b) pyrometallurgy

Question 52.
Which process of purification is represented by the following reaction

(a) Zone refining
(b) Mond’s process
(c) Cupellation
(d) van Arkal process
Answer:
(c) Cupellation

Question 53.
Chromatography is a useful method for purification of elements which are
(a) very reactive
(b) available in minute quantities
(c) present in abundance
(d) highly electropositve
Answer:
(b) available in minute quantities

Question 54.
A number of elements are available in earth’s crust but most abundant elements are……………..
(a) Al and Fe
(b) Al and Cu
(c) Fe and Cu
(d) Cu and Ag
Answer:
(a) Al and Fe

Question 55.
In the extraction of copper from its sulphide ore, the mental is formed by the reduction of Cu₂O with………………….
(a)FeS
(b)CO
(c) Cu₂S
(d) SO₂
Answer:
(c) Cu₂S

Question 56.
Electrolytic refining is used to purify which of the following metals ?
(a) Cu and Zn
(b) Ge and Si
(c) Zr and Ti
(d) Zn and Hg
Answer:
(a) Cu and Zn

Question 57.
Below point ‘A’ FeO can_________
(a) be reduced by carbon monoxide only
(b) be redued by both carbon monoxide and carbon
(c) be reduced by carbon only
(d) not be reduced by both carbon and carbon monoxide
Answer:
(a) be reduced by carbon monoxide only