CBSE Questions for Class 12 Engineering Chemistry General Principles And Processes Of Isolation Of Elements Quiz 3 - MCQExams.com

 During extraction of metals, electrolytic refining is used to obtain pure metals. What is the electrolyte used?
  • Silver salt
  • Copper(ll) sulphate
  • Sodium chloride
  • Both A and B
What is anode mud?
  • Dust of anode
  • Metal of anode
  • Impurities collected at anode in electrolysis during purification of metals
  • All of these
Aluminium is used in thermite welding because:
  • aluminium is a light metal
  • aluminium has more affinity for oxygen
  • aluminium is a strong oxidizing agent
  • aluminium is a reactive metal
Which of the following ore is best concentrated by froth flotation method ?
  • Galena
  • Cassiterite
  • Magnetite
  • Zinc blende
In bessemer converter, oxides of manganese and silicon are removed as: 
  • manganese silicate
  • silica
  • magnesium oxide
  • none of these
Which of the following gases is responsible for the flame at the mouth of Bessemer converter?
  • Carbon monoxide
  • Carbon dioxide
  • Chlorine
  • Oxygen
In froth floatation process, gangue articles are wetted by pine oil.
  • True
  • False
Anodic product in the electrolytic reduction of alumina is:
  • $$CO_{2}, \ \ O_{2}$$
  • $$O_{2}$$
  • $$F_{2}$$
  • $$O_{2},\ \ 4F_{2}$$
Mercury has low boiling point. Therefore, it can be purified by the process of:
  • Liquation
  • Polling
  • Oxidation
  • Distillation
The role of coke in the electrolytic reduction of alumina is to _______.
  • provide heat for melting of alumina
  • prevent loss of heat
  • prevent burning of carbon rods
  • reduce alumina to metal
In Goldschmidt alumina thermic process, thermite mixture is:
  • 3 parts $$Fe_{3}O_{3}$$ and 2 parts $$Al$$
  • 3 parts $$Al_{2}O_{3}$$ and 4 parts $$Al$$
  • 1 part $$Fe_{2}O_{3}$$ and 2 part $$Al$$
  • 3 parts $$Fe_{2}O_{3}$$ and 1 part $$Al$$
Which metal is adds to gold to make hard?
  • Copper
  • Nickel
  • Zinc
  • Silver
The thickness of cathode increases in :
  • electrorefining of copper
  • electroplating of copper
  • anodizing of copper
  • none of the above
In froth flotation process, pine oil is usually added to the gangue particles in the ore.
  • True
  • False
State the given statement is true or false.
Statement: Mercuric oxide is reduced by thermal decomposition.
  • True
  • False
In the purification of metals, during distillation, metal is heated in a retort and its vapours are separately condensed in a receiver.
  • True
  • False
In metallurgy, the concentration of ore is followed by the dressing of ore.
  • True
  • False
The following flow chart represents the extraction of _______.

Froth flotation
       $$\downarrow$$
Roasting
       $$\downarrow$$
Smelting
       $$\downarrow$$
Bessemerization
       $$\downarrow$$
Electrolytic refining
  • Copper
  • Zinc
  • Iron
  • Aluminium
Metal used for making electric cable is:
  • Lead
  • Silver
  • Tin
  • Copper
Metals which have a low melting point are refined by liquation.
  • True
  • False
The process used in purifying metals by electrolysis is called:
  • electroplating
  • electrometallurgy
  • electrorefining
  • electro-deposition
 In electro-refining, thick sheets of pure copper are obtained at :
  • cathode
  • anode
  • electrode
  • none of the above
Which of the following statements is incorrect?
  • Calamine and Siderite are carbonates.
  • Argentite and Cuprite are oxides.
  • Zinc blende and Pyrites are sulphides.
  • Malachite and Azurite are ores of copper.
In the extraction of some metals from their ores, coke can be used as:
  • Oxidizing agent
  • Reducing agent
  • Catalyst
  • Flux
The oil used in the froth flotation method for the purification of ore is:
  • coconut oil
  • olive oil
  • pine oil
  • castor oil
State whether the statement is true or false:
Phosphorus mostly exists in free state.
  • True
  • False
In which of the following minerals, aluminium is not present?
  • Cryolite
  • Mica
  • Feldspar
  • Fluorspar
Which of the following element is found in its native state?
  • Silver
  • Gold
  • Sodium
  • Both (A) and (B)
Which type of ores are concentrated by froth flotation process?
  • Carbonates
  • Sulphides
  • Oxides
  • Phosphates
Phosphoric acid is prepared on large scale from __________.
  • phosphorus
  • dolomite
  • phosphorite
  • malachite
The order of processes involved in the dressing of an ore are :
(i) grinding and crushing           (ii) hand picking                (iii) pulverization
  • (i), (ii), (iii)
  • (i), (iii), (ii)
  • (ii), (iii), (i)
  • (ii), (i), (iii)
In the electrolytic reduction of alumina, the electrolyte is covered with coke powder because, it __________.
  • prevents oxidation of aluminium formed
  • reacts with aluminium forming aluminium carbide
  • prevents heat loss from the electrolyte
  • none of the above
Froth floatation process for the concentration of ores is an illustration of physical phenomenon of:
  • adsorption
  • absorption
  • conagulation
  • sedimentation
Which one of the following ore is not concentrated by froth floatation process?
  • Copper pyrites
  • Galena
  • Pyrolusite
  • Zinc blende
Which ore is concentrated by froth flotation method?
  • Horn silver
  • Bauxite
  • Cinnabar
  • Haemattie
Which one of the following ores is best concentrated by froth flotation method?
  • Galena
  • Cassiterite
  • Magnetie
  • Malachite
What is the principle of zone refining of metals?
  • Greater mobility of the pure metal than that of the impurity
  • Higher melting point of the impurity than that of the pure metal
  • Greater noble character of the solid metal than that of the impurity
  • Greater solubility of the impurity in the molten state than in the solid
Which of the following process is used for concentration of ore?
  • Froth flotation
  • Electrolytic methods
  • Smelting
  • Hoop's process
An ore of tin containing $$FeCrO_4$$ is concentrated by:
  • magnetic separation
  • froth floatation
  • electrostatic
  • gravity separation
Which of the following method used for the concentration of copper pyrites?
  • Magnetic seperation
  • Gravity seperation
  • Froth Floatation process
  • None
Zone refining method is used for the ores of:
  • Silicon
  • boron
  • gallium
  • all of these
Electrolytic reduction of alumina to aluminium by Hall-Heroult's process is carried out _____________.
  • in the presence of sodium chloride
  • in the presence of flourite
  • in the presence of cryolite which forms a melt with lower melting temperature
  • in the presence of cryolite which forms a melt with higher melting temperature
Free energy change of Hg and Mg for the conversion to oxides the slope of $$\Delta G$$ vs. T has been changes above the boiling points of the given metal because -
122808.png
  • Above the boiling point of the metal, the entropy of metal become more
  • Above the boiling point of the metal, the entropy is constant
  • Above the boiling point of the metal the entropy is decreased
  • All of these
Collectors are the substances which combine with sulphide ore and make them water repellant. Which of the following substance can act as collector?
  • Sodium ethyl xanthate
  • Sodium xenate
  • Sodium pyrophosphate
  • Adsorption
In froth-flotation process, pine oil functions as a(an):
  • activator
  • frothing agent
  • collector
  • agitator
For the conversion of Ca(s) to CaO(s) which of the following represent the $$\Delta G$$ vs. T
122808.png
Sulphide ores are common for metals:
  • Ag, Cu and Pb
  • Ag, Cu and Sn
  • Ag, Mg and Pb
  • none
Ellingham diagram represents:
  • Change of $$\Delta G $$ with temperature
  • Change of $$\Delta H $$ with temperature
  • Change of $$\Delta G $$ with pressure
  • Change of $$(\Delta G- T\Delta S) $$ with temperature
Zone refining is a method to obtain:
  • ultra pure boron
  • ultra pure lead
  • ultra pure silicon
  • all
Gold is extracted by hydrometallurgical process, based on its property:
  • of being electropositive
  • of being less reactive
  • to form complex which are water soluble
  • None of these
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