CBSE Class 12 Chemistry General Principles and Processes of Isolation of Elements MCQs Set A

Question : Sulfide ores are common for the metals

(a) Ag, Cu and Pb 
(c) Ag, Cu and Sn
(b) Ag, Mg and Pb
(d) Al, Cu and Pb

Answer : A

Question : The undesired material which is present with the element in its ore is known as ____.
(a) slag
(b) gangue
(c) flux
(d) sludge
Answer : B

Question : Ellingham diagrams are plots drawn between ____ and ____ for formation of oxides.
(a)Temperature and change in enthalpy
(b)Change in Gibbs free energy and Pressure
(c)Change in Gibbs free energy and temperature
(d)Change in enthalpy and pressure
Answer : B

Question :   In the electrolysis of aluminium, the anodes in the cell have to be replaced frequently because ____.
(a)they melt in the high temperature inside the cell.
(b)they are burned away by O reacting with the carbon anode to form CO₂ gas.
(c)they get coated in a thick crust of solid Al₂O₃.
(d)the Al formed on them has to be removed.
Answer : B

Question : During the formation of metal oxides from metal and oxygen, what happens to the change in Gibbs free energy with the little increase of temperature?
(a)Increases
(b)Decreases
(c)Remains same
(d)Insufficient data
Answer : A

Question : Which of the following is not an ore of iron?
(a)Siderite
(b)Haematite
(c)Limonite
(d)Dolomite
Answer : D

Question :  Distillation is very useful for low boiling metals like____.
(a)zinc and mercury
(b)sodium and magnesium
(c)iron and copper
(d)gold and silver
Answer : A

Question : Which one of the following is an ore of silver ?
(a) Argentite
(b) Stibnite
(c) Haematite
(d) Bauxite

Answer : A

Question : Cinnabar is an ore of
(a) Hg
(b) Cu
(c) Pb
(d) Zn

Answer : A

Question : An example of an oxide ore is
(a) Bauxite
(b) Malachite
(c) Zinc blende
(d) Feldspar

Answer : A

Question : The natural materials from which an element can be extracted economically are called
(a) ores
(b) minerals
(c) gangue
(d) None of these

Answer : A

Question : The most abundant metal on the surface of the earth is
(a) Fe
(b) Al
(c) Ca
(d) Na

Answer : B

Question : Which of the following is an ore of tin ?
(a) Carborundum
(b) Epsomite
(c) Cassiterite
(d) Spodumene

Answer : C

Question : Which of the following is chalcopyrite?
(a) CuFeS₂
(b) FeS₂
(c) KMgCl₃.6H₂O
(d) Al₂O₃.2H₂O

Answer : A

Question : Haematite is the ore of
(a) Pb
(b) Cu
(c) Fe
(d) Au

Answer : C

Question : Composition of azurite mineral is
(a) CuCO₃CuO
(b) Cu(HCO₃)₂. Cu(OH)₂
(c) 2CuCO₃.Cu(OH)₂
(d) CuCO₃. 2Cu(OH)₂

Answer : C

Question : Which one of the following is a mineral of iron ?
(a) Malachite
(b) Cassiterite
(c) Pyrolusite
(d) Magnetite

Answer : D

Question : All ores are minerals, while all minerals are not ores because
(a) the metal can’t be extracted economically from all the minerals
(b) minerals are complex compounds
(c) the minerals are obtained from mines
(d) all of these are correct

Answer : A

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

Answer : A

Question : The impurities associated with mineral used in metallurgy are called collectively?
(a) Slag
(b) Flux
(c) Gangue
(d) Ore

Answer : C

Question : The most abundant element in the earth’s crust (by weight) is
(a) Si
(b) Al
(c) O
(d) Fe

Answer : C

Question : Malachite is an ore of
(a) iron
(b) copper
(c) mercury
(d) zinc

Answer : B

Question : Cassiterite is an ore of
(a) Mn
(b) Ni
(c) Sb
(d) Sn

Answer : D

Question : Galena is an ore of
(a) Pb
(b) Hg
(c) Zn
(d) None of these

Answer : A

Question : The metal always found in the free states is
(a) Au
(b) Ag
(c) Cu
(d) Na

Answer : A

Question : Matrix is defined as –
(a) the unwanted foreign material present in the ore
(b) the flux added to remove the unwanted impurities from ore
(c) the slag formed as a result of the reaction of flux with gangue
(d) the material used in the reduction of metal oxide to metal

Answer : A

Question : Which of the following pair is incorrectly matched ?

(a) Magnetite – Fe₃O₄

(b) Copper glance – Cu₂S

(c) Calamine – ZnCO₃

(d) Zincite – ZnS

Answer : C

Question : Which one of the following ores is best concentrated by froth-flotation method ?

(a) Galena

(b) Cassiterite

(c) Magnetite

(d) Malachite

Answer : C

Question : Froth floatation process is used for the metallurgy of

(a) chloride ores

(b) amalgams

(c) oxide ores

(d) sulphide ores

Answer : D

Question : Cassiterite is concentrated by

(a) levigation

(b) electromagnetic separation

(c) floatation

(d) liquefaction

Answer : B

Question : While extracting an element from its ore, the ore is grounded and leached with dil. potassium cyanide solution to form the soluble product potassium argento cyanide. The element is

(a) Lead

(b) Chromium

(c) Manganese

(d) Silver

Answer : D

Question : The method of concentrating the ore which makes use of the difference in density between ore and impurities is called

(a) levigation

(b) leaching

(c) magnetic separation

(d) liquifaction

Answer : A

Question : Leaching is a process of

(a) reduction

(b) concentration

(c) refining

(d) oxidation

Answer : B

Question : Which one of the following ores is concentrated by chemical leaching method?

(a) Galena

(b) Copper pyrite

(c) Cinnabar

(d) Argentite

Answer : D

Question : Electromagnetic separation is used in the concentration of

(a) copper pyrites

(b) bauxite

(c) cassiterite

(d) cinnabar

Answer : C

Question : For which ore of the metal, froth floatation method is used for concentration?

(a) Horn silver

(b) Bauxite

(c) Cinnabar

(d) Heamatite

Answer : C

Question : Which of the following metal is leached by cyanide process ?

(a) Ag

(b) Na

(c) Al

(d) Cu

Answer : A

Question : Which one of the following ores is not concentrated by froth floatation process?

(a) Copper pyrites

(b) Pyrargyrite

(c) Pyrolusite

(d) Zinc blende

Answer : C

Question : In froth flotation process many chemicals (frother , collector,activator, and depressant) are used. Which of the following is a frother ?

(a) CuSO₄

(b) NaCN+ alkali

(c) Pine oil

(d) Potassium xanthate

Answer : C

Question : Froth flotation process is based on

(a) wetting properties of ore particle

(b) specific gravity of ore particles

(c) magnetic properties of ore particles

(d) electrical properties of ore particles

Answer : A

Question : In the froth flotation process of concentration of ores, the ore particles float because they:

(a) are light

(b) are insoluble

(c) have the surface which is not wetted easily

(d) have a constant electrical charge

Answer : C

Question : Main function of roasting is

(a) to remove volatile substances

(b) oxidation

(c) reduction

(d) slag formation

Answer : A

Question : Roasting is generally done in case of the

(a) oxide ores

(b) silicate ores

(c) sulphide ores

(d) carbonate ores

Answer : C

Question : Heating of pyrites in air for oxidation of sulphur is called

(a) roasting

(b) calcination

(c) smelting

(d) slagging

Answer : A

Question : The role of calcination in metallurgical operations is

(a) to remove moisture

(b) to decompose carbonates

(c) to drive off organic matter

(d) to decompose carbonates and drive off moisture and organic matter

Answer : D

Question : General method for the extraction of metal from oxide ore is

(a) carbon reduction

(b) reduction by aluminium

(c) reduction by hydrogen

(d) electrolytic reduction

Answer : A

Question : Function of the flux added during smelting is

(a) to make ore porous

(b) to remove gangue

(c) to make reduction easier

(d) to precipitate slag

Answer : B

Question : Process followed before reduction of carbonate ore is

(a) calcination

(b) roasting

(c) liquation

(d) polling

Answer : A

Question : Calcination is the process in which :

(a) ore is heated above its melting point to expel H₂O or CO₂ or SO₂

(b) ore is heated below its melting point to expel volatile impurities

(c) ore is heated above its melting point to remove S, As and Sb as SO₂ ,As2O₃ and Sb2O₃ respectively

(d) ore is heated below its melting point to expel H₂O or CO₂

Answer : D

Question : When a metal is to be extracted from its ore and the gangue associated with the ore is silica, then

(a) an acidic flux is needed

(b) a basic flux is needed

(c) both acidic and basic fluxes are needed

(d) Neither of them is needed

Answer : B

Question : Which of the following fluxes is used to remove acidic impurities in metallurgical process?

(a) Silica

(b) Lime stone

(c) Sodium chloride

(d) Sodium carbonate

Answer : B

Question : Which of the following reactions is an example for calcination process ?

(a) 2Ag + 2HCl + (O) → 2AgCl + H₂O

(b) 2Zn + O₂ →2ZnO

(c) 2ZnS + 3O₂ →2ZnO + 2SO₂

(d) MgCO₃ → MgO+CO₂

Answer : D

Question : After partial roasting the sulphide of copper is reduced by

(a) cyanide process

(b) electrolysis

(c) reduction with carbon

(d) self reduction

Answer : D

Question : Hydro-metallurgical process of extraction of metals is based on

(a) complex formation

(b) hydrolysis

(c) dehydration

(d) dehydrogenation

Answer : A

Question : 2CuFeS₂ + O₂ → Cu₂S + 2FeS +SO₂ Which process of metallurgy of copper is represented by above equation?

(a) Concentration

(b) Roasting

(c) Reduction

(d) Purification

Answer : B

Question : Which of the following is not used as a collector ?

(a) Pine oil

(b) Xanthates

(c) Cresols

(d) Fatty acids

Answer : B

Question : According to Ellingham diagram, the oxidation reaction of carbon to carbon monoxide may be used to reduce which one of the following oxides at the lowest temperature ?

(a) Al₂O₃

(b) Cu₂O

(c) MgO

(d) ZnO

Answer : B

Question : The process does not involve a catalyst is :

(a) Haber process   
(b) Contact process
(c) Thermite process
(d) Ostwald process

Answer : C

Question : Chief ore of Al is :

(a) cryolite 
(b) bauxite
(c) feldspar
(d) kaolin

Answer : B

Question : Froth floatation is a process of:

(a) Oxidation
(b) Reduction
(c) Refining  
(d) Concentration

Answer : D

Question : Flux is used to remove :

(a) basic impurities
(b) acidic impurities
(c) all types of impurities
(d) acidic and basic both impurities

Answer : D

Question : Mac Arthur process is used for the extraction of:
(a) Au
(b) Pt
(c) Cu
(d) Zn

Answer : A

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

Answer : C

Question : Which of the following is a carbonate ore?
(a) Pyrolusite
(b) Malachite
(c) Diaspore
(d) Cassiterite

Answer : B

Question : Carbon and CO gas are used to reduce which of the following pairs of metal oxides for extraction of metals?
(a) FeO, SnO   
(b) SnO, ZnO
(c) BaO, Na₂O₂
(d) FeO, ZnO

Answer : D

Question : In metallurgical process of aluminium, cryolite is mixed with alumina in its molten state, because it

(a) decreases the amount of alumina
(b) oxidises the alumina
(c) increases the melting point of alumina
(d) decreases the melting point of alumina

Answer : D