CBSE Questions for Class 12 Engineering Chemistry General Principles And Processes Of Isolation Of Elements Quiz 6 - MCQExams.com

Which one of the following metals is used as foil in wrapping cigarettes and confectionery?
  • Silver
  • Steel
  • Aluminium
  • Copper
Which of the following minerals occur naturally mainly in combined form? 
Aluminium 
Gold 
Calcium 
Sodium
  • 1, 2 and 3 only
  • 1 and 3 only
  • 2 and 4 only
  • 1, 3 and 4
Removal of impurities from ore is known as:
  • Crushing 
  • Concentration of ore
  • Washing
  • Grinding
In thermite process reducing agent used is:
  • $$C$$
  • $$CO$$
  • $$Al$$
  • none of these
Any physical and chemical process by which low grade ores are concentrated, is __________.
  • froth flotation
  • crushing and then screening
  • hand picking
  • washing in zigs
Which of the following methods is used for obtaining metals of very high purity?
  • Distillation
  • Zone refining
  • Liquation
  • Electrolytic refining
Which statement is true?
  • Aluminium is the most abundant metal in the earth's crust.
  • Oxygen is the most abundant non-metal in the earth's crust.
  • Ammonia $$(NH_3)$$ and methane $$(CH_4)$$ are covalent hydrides.
  • All of these.
Which of the following methods is based on the principle of the difference in the wetting properties of the ore and gangue particles with water and oil?
  • Magnetic separation
  • Froth floatation process
  • Hydraulic washing
  • None of these
RCC is:
  • the concrete having an iron framework inside it as a support
  • the crushed cement in which more gravel is added
  • prepared by adding calcium chloride to the limestone and calcium silicate
  • none of the above
Liquation is used to refine:
  • iron
  • tin
  • copper
  • gold
Which of these is obtained by electrolytic reduction of its compound?
  • $$Cu$$
  • $$Au$$
  • $$Mg$$
  • $$Bi$$
Aluminium is extracted by :
  • Heating sodium aluminium silicate to a high temperature
  • Treating cryolite with sodium hydroxide solution under pressure
  • Heating aluminium oxide with coke in a furnace
  • The electrolysis of molten aluminium oxide in fused cryolite
The most abundant metal on the earth is:
  • iron
  • gold
  • aluminium
  • copper
Which of the following metals exist in their native state in nature?
  • Cu and Au
  • Au and Zu
  • Au and Ag
  • Ag and Cu
A metal obtained by auto reduction or self reduction _______________.
  • Na
  • Zn
  • Fe
  • Cu
Sequence the following steps involved generally in the extraction of a metal in pure form from its ore.
(a) The metal obtained from its oxide require further purification for end use.
(b) The ore should be converted to its oxide form.
(c) The ore is beneficial to us if it is handpicked then metal crushed and ground, and later subjected to pulverization as per the requirement
(d) The ore in the form of oxide is required to be reduced.
(e) Dressed ore is required for it to be concentrated.
  • e c b d a
  • c e b d a
  • c e b a d
  • c e d b a
In the electrolytic reduction of alumina, the electrolyte is covered with coke powder because, if :
  • prevents oxidation of aluminium formed
  • reacts with aluminium forming aluminium carbide
  • prevents heat loss from electrolyte
  • None of the above
A mixture of sand and salt can be separated by:
  • Sublimation
  • Sieving
  • Dissolving salt and sand mixture in water and then filtration
  • Dissolving salt in water and then distillation
Which of the following method is used for extracting metals from ores?
  • Reduction
  • Melting
  • Electrolysis
  • Both $$A$$ and $$C$$
What is electrolysis$$?$$
  • Decomposition of substance by passing electricity
  • Decomposition of substance by heating
  • Decomposition of substance by redox reaction
  • Addition of hydrogen
Prior to reduction, metal sulphide and carbonates are converted into oxides because:
  • carbonates, sulphides are heavy molecules
  • it is easier to obtain a metal from its oxide as compared to its sulphides and carbonates
  • it is easy to heat oxide compared to sulphides and carbonates
  • both $$A$$ and $$B$$
What is concentration of ore?
  • Increasing the concentration of metal
  • Reducing the concentration of metal
  • Reducing hydrogen ions
  • Both $$A$$ and $$C$$
_________ is the removal of oxygen for extraction of metal from ore.
  • Reduction
  • Electrolysis
  • Oxidation
  • Distillation
Ores contain a large amount of impurities, which is called as:
  • ore
  • gangue
  • dust
  • particulate
Which of the following statement is not correct about Ellingham diagram?
  • $$\Delta G$$ increases with an increase in temperature
  • It consists of plots of $$\Delta_{f}G^{\circ}$$ vs $$T$$ for formation of oxides
  • A coupling reaction can be well expressed by this diagram
  • It express the kinetics of the reduction process
An ore on heating in air forms $$SO_{2}$$. State the process that will be used for its concentration.
  • Hydrautic washing
  • Magnetic separation
  • Froth floatation
  • None of the above
The purest zinc is made by:
  • Electrolytic refining
  • Zone refining
  • The van Arkel method
  • The Mond process
Ores in the form of sulphide and carbonate are converted into:
  • water
  • oxides
  • aldehyde
  • alcohol
In froth floatation process for the purification of ores, the particles of ore float because :
  • their surface is not easily wetted by water
  • they are light
  • they are insoluble
  • they bear electrostatic charge
Which one of the following ores is concentrated by froth floatation process?
  • Magnesite
  • Magnetic
  • Galena
  • Malachite
Define roasting.
  • Heating of sulphide ores in the presence of excess air to convert them into oxides
  • Heating of carbonate ores in the limited supply of air to convert them into oxides
  • Heating of oxides of metals to turn them into metal
  • Heating of carbonate ores in the limited supply of air to convert them into sulphide
A number of elements available in earth's crust but most abundant elements are:
  • $$Al$$ and $$Fe$$
  • $$Al$$ and $$Cu$$
  • $$Fe$$ and $$Cu$$
  • $$Cu$$ and $$Ag$$
The ratio of $$Fe_{2}O_{3}$$ and $$Al$$ by weight, in thermite is about:
  • $$1 : 3$$
  • $$1 : 2$$
  • $$3 : 1$$
  • none of the above
___________ metals occur free in nature.
  • Alkali
  • Noble
  • Iron
  • Aluminum
A mixture of $$Sn$$ and $$Pb$$ can be separated by __________ method.
  • hank picking
  • distillation
  • liquation
  • winnowing
In froth floatation process, gangue particles are wetted by pine oil.
  • True
  • False
The first step in the hydrometallurgical process is___________.
  • Filteration
  • Electrolysis
  • Reduction
  • Leaching
The method used for the concentration of sulphide ores is:
  • froth floatation
  • smelting
  • magnetic separatio
  • gravity separation
Cinnabar $$(HgS)$$ is heated in air, it is first converted into ________ which is then reduced to _______ on further heating.
  • $$HgO$$, $$Hg$$
  • $$HgO$$, $$Hg_2O$$
  • $$Hg_2O$$, $$Hg$$
  • $$Hg_2O$$, $$HgO$$
During electrolytic refining of Alumina, the molten electrolyte used contains _______ .
  • Cryolite
  • Fluorspar
  • Pure alumina
  • All of the above
Iron can be purified by the method of liquation.
  • True
  • False
During electrolytic reduction of alumina, ___________.
  • Al is formed at cathode and oxygen is formed at anode
  • Al is formed at anode and oxygen is formed at cathode
  • Al is formed at cathode and hydrogen is formed at anode
  • Al is formed at anode and hydrogen is formed at cathode
Mercury has low boiling point. Therefore it can be purified by the process of:
  • liquation
  • polling
  • oxidation
  • distillation
During calcination:
  • carbonate ores are changed into oxides
  • oxide ores are changed into carbonates
  • carbonate ores are changed into sulphides
  • oxide ores are changed into sulphides
Metal oxide can be reduced by __________.
  • $$Fe$$
  • $$Sn$$
  • $$C$$
  • All of these
The ore that is concentrated by the froth floatation process is:
  • chalcopyrites
  • cryolite
  • cuprite
  • calamine
The function of potassium ethyl xanthate in froth floatation process is to make the ore :
  • attracted towards water
  • water repellant
  • lighter
  • heavier
Aluminium powder is used in thermite welding because :
  • it is a strong reducing agent
  • it is a strong oxidising agent
  • it is corrosion resistant
  • it is a good conductor of heat
The process of zone refining is used in the purification of :
  • $$Al$$
  • $$Ge$$
  • $$Cu$$
  • $$Ag$$
Point out the correct statement:
  • Below $$710^{\circ}C$$, $$C$$ is better reducing agent than $$CO$$
  • Below $$710^{\circ}C$$, $$CO$$ is better reducing agent than $$C$$
  • Below $$710^{\circ}C, CO$$ is an oxidising agent
  • Below $$710^{\circ}C, CO_{2}$$ is a reducing agent
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