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