MCQExams
0:0:1
CBSE
JEE
NTSE
NEET
Practice
Homework
×
CBSE Questions for Class 12 Engineering Chemistry General Principles And Processes Of Isolation Of Elements Quiz 1 - MCQExams.com
CBSE
Class 12 Engineering Chemistry
General Principles And Processes Of Isolation Of Elements
Quiz 1
The refining method used when the metal and the impurities have low and high melting temperatures, respectively, is :
Report Question
0%
zone refining
0%
liquation
0%
distillation
0%
vapour phase refining
Explanation
$$\rightarrow $$ metal with low melting point containing impurities of high melting point can be purified by liquation because
$$\rightarrow $$ Liquation separation is based on differences in the melting point and density of alloy and on the low level of mutual solubility of the constituents.
So, option 2 is correct.
The correct statement is :
Report Question
0%
leaching of bauxite using concentrated $$NaOH$$ solution gives sodium aluminate and sodium silicate
0%
The blistered appearance of copper during the metallurgical process is due to the evolution of $$CO_2$$
0%
pig iron is obtained from cast iron
0%
the Hall-Heroult process is used for the production of aluminium and iron.
Explanation
(1) During leaching when bauxite is treated with concentrated $$NaOH$$, then sodium aluminate and sodium silicate is formed in the soluble form, whereas $$Fe_2O_3$$ is precipitated.
(2) The blistered appearance of copper during the metallurgical process is due to the evolution of $$SO_2$$.
(3) Cast iron is obtained from pig iron.
(4) Hall-Heroult process is used for the production of only aluminium.
Which one of the following ores is best concentrated by froth floatation method?
Report Question
0%
Siderite
0%
Galena
0%
Malachite
0%
Magnetite
Explanation
$$Explanation\ for \ correct\ option:$$
In the Froth floatation method, the finely ground ore is mixed with water, oil and foam foaming agent.
Then the mixture is stirred, during stirring foam is gets formed which contains ore. The ore comes out with foam and heavily dense impurities remain bottom of the container.
The froth floatation method is useful for low dense ores. Therefore Galena (i.e. $$PbS$$) is low dense and can be separated by this method.
$$Explanation\ for \ incorrect\ option:$$
Siderite ( $$FeCO_3$$), Malachite (
$$Cu_2CO_3(OH)_2$$) and Magnetite ($$Fe_3O_4$$) are dense ores and not suitable for froth floatation method.
$$Final\ Answer:$$ Option $$B$$.
Fusion of $$MnO_{2}$$, with $$KOH$$ in presence of $$O_{2}$$ produces a salt $$W$$. Alkaline solution of $$W$$ upon electrolytic oxidation yields another salt $$X$$. The manganese containing ions present in $$W$$ and $$X$$, respectively are $$Y$$ and $$Z$$. Correct statement(s) is (are)
Report Question
0%
In both $$Y$$ and $$Z, \alpha-bonding$$ occurs between $$p-orbitals$$ of oxygen and d-orbitals of manganese
0%
Both $$Y$$ and $$Z$$ are coloured and have tetrahedral shape
0%
In aqueous acidic solution, $$Y$$ undergoes disproportionation reaction to give $$Z$$ and $$MnO_{2}$$
0%
$$Y$$ is diamagnetic in nature while $$Z$$ is paramagnetic
Explanation
-
A tin chloride $$Q$$ undergoes the following reaction (not balanced)
$$Q + Cl^{-} \rightarrow X$$
$$Q + Me_{3}N \rightarrow Y$$
$$Q + CuCl_{2}\rightarrow Z + CuCl$$
$$X$$ is monoanion having pyramidal geometry. Both $$Y$$ and $$Z$$ are neutral compounds. Choose the correct options(s)
Report Question
0%
The central atom in $$X$$ is $$sp^{3}$$ hybridized
0%
There is a coordinate bond in $$Y$$
0%
The oxidation state of the central atom in $$Z$$ is $$+2$$
0%
The central atom in $$Z$$ has one lone pair of electrons
Explanation
$$\underset {(P)}{SnCl_{2}} + Cl^{-} \rightarrow \underset {(X)}{SnCl_{3}^{-}}$$
$$\underset {(P)}{SnCl_{2}} + Me_{3}N \rightarrow \underset {(Y)}{SnCl_{2} [N(CH_{3})_{3}]}$$
$$\underset {(P)}{SnCl_{2}} + 2CuCl_{2}\rightarrow \underset {(Z)}{SnCl_{4}} + CuCl$$.
Bell metal is an alloy of:
Report Question
0%
Sn and Pb
0%
Cu and Pb
0%
Sn and Cu
0%
Fe, Sn and Cu
Explanation
Bell metal is a hard alloy used for making bells and related instruments, such as cymbals. It is a form of bronze, usually in approximately a 4:1 ratio of copper to tin. Bell metal ore is a sulfide of tin, copper, and iron called stannite.
Unwanted material with ore is called as ______ .
Report Question
0%
Gangue
0%
Rust
0%
Slag
0%
Silica
Explanation
Ores contain some impurities in the form of clay or rocky material known as gangue.
In electrolytic refining of any metal impure metal is taken as ...............
Report Question
0%
anode
0%
cathode
0%
solution
0%
both B and C
Explanation
In electrolytic refining, impure metal is of positive charged anode and pure metal is of negative charged cathode.
Complete the following statement with an appropriate word/term to be filled in the blank space.
Froth floatation process is used for the concentration of _________ ores.
Report Question
0%
Sulphide
0%
Oxide
0%
Carbonate
0%
All the above
Explanation
Froth flotation is a process for selectively separating hydrophobic materials from hydrophilic.
In this, sulphide ores of copper, zinc and lead are concentrated by preferential wetting of ore by pine oil.
Option A is correct.
Reaction takes place in aluminothermic process is also known as _______ .
Report Question
0%
thermite reaction
0%
thermal reaction
0%
decomposition reactions
0%
catalytic reaction
Explanation
Thermite reaction also known as Goldschmidt reaction is a highly exothermic reaction which involves reaction between iron oxide(rust) with aluminium to produce molten iron.
Cinnabar is an ore of :
Report Question
0%
Hg
0%
Cu
0%
Pb
0%
Zn
Explanation
Cinnabar HgS is an ore of Hg.
Matrix is defined as:
Report Question
0%
the unwanted foreign material present in the ore
0%
the flux added to remove the unwanted impurities from ore
0%
the slag formed as a result of the reaction of flux with gangue
0%
the material used in the reduction of metal oxide to metal
Explanation
The ore that exists inside our earth contains dust, stone, quartz and other foreign materials. The impurities are called gangue or matrix in the ore. During the concentration process, care is taken to remove the matrix from the ore.
In the combined state, zinc is mainly found as :
Report Question
0%
chloride
0%
bromide
0%
oxide
0%
sulphide
Explanation
The most common ore of zinc is zinc blend or zinc sulfide. Zinc sulfide is main form of zinc found in nature.
Which of the following metal occurs in native state?
Report Question
0%
Ca
0%
Au
0%
Zn
0%
Al
Explanation
Gold because of its inert nature does not combine with oxygen, hydrogen or humidity easily and thus occur in native state or free state.
Froth flotation method is used for the concentration of
:
Report Question
0%
oxide ores
0%
sulphide ores
0%
sulphate ores
0%
halide ores
Explanation
Froth floatation is based on the principle of the difference in the wetting properties of the ore and gangue particles with the water and oil. This method is used for those metals whose ore gets preferably wet by the oil and the gangue by the water. The sulphide ores get preferably wet by the oil and the gangue with the water.
Alumina thermite process involves reduction of chromium(II) oxide with ..................... .
Report Question
0%
copper
0%
zinc
0%
iron
0%
aluminium
Explanation
Aluminium is used in thermite process as it has high boiling point, low cost and more reactivity than many of the d-block metals. Oxidizers used are boron(III) oxide, chromium(III) oxide, iron(II,III) oxide and copper(II) oxide.
Which one is make a conducting solution?
Report Question
0%
Pure aluminium oxide
0%
Coke
0%
Cryolite
0%
All of these
Explanation
Pure alumina melts at about $$2000^oC$$ and is a bad conductor of electricity. If fused cryolite and fluorspar is added, the mixture melts at $$900^oC$$ and $$Al_2O_3$$ becomes a good conductor of electricity.
The composition of thermite mixture is
Report Question
0%
Iron (III) oxide and aluminium powder in the ratio 1 : 3.
0%
Aluminium powder and iron (III) oxide in the ration 1 : 3.
0%
Aluminium powder and barium peroxide in the ratio 1 : 3.
0%
Barium peroxide and aluminium in the ratio 1 : 3.
Explanation
Thermite mixture is 1 : 3 ratio of Al powder and ferric oxide.
The electrolyte used in electrolytic refining of impure aluminium is __________.
Report Question
0%
$$Al_2O_{3} + CaF_{2}$$
0%
$$Na_{3}AlF_{6} + CaF_{2}$$
0%
$$Al_2O_{3}, Na_{3}AlF_{6}\ and\ CaF_{2}$$
0%
Any aluminium salt is molten state
Explanation
In the metallurgy of aluminium, purified $$Al_2O_3$$ is mixed with $$Na_3AlF_6$$ or $$CaF_2$$ which lowers the melting point of the mix and brings
conductivity.
In the upper region of blast furnace the gas helps in the reduction of iron oxide to iron is:
Report Question
0%
carbon dioxide
0%
carbon monoxide
0%
hydrogen
0%
oxygen
Explanation
The hot carbon monoxide is the reducing agent for the iron ore and reacts with the iron oxide to produce molten iron and carbon dioxide. Depending on the temperature in the different parts of the furnace (warmest at the bottom) the iron is reduced in several steps.
Hence, the correct option is $$(B)$$
Sulphur molecule exists as :
Report Question
0%
$$S_2$$
0%
$$S$$
0%
$$S_6$$
0%
$$S_8$$
Explanation
Sulphur molecule exists as $$S_8$$.
Concentration by froth floatation is applicable for which of the following ores?
Report Question
0%
$$Al_{2}O_{3}$$
0%
$$Te_{3}O_{4}$$
0%
$$Te_{2}O_{3}.3H_{2}O$$
0%
$$ZnS$$
Explanation
This method is used for those metals whose ore gets preferably wetted by the oil and the gangue by the water. The sulphide ores preferably wetted by the oil and the gangue with the water.
In thermite process, the reducing agent is:
Report Question
0%
C
0%
Al
0%
Na
0%
Mg
Explanation
Hint: The thermite process is widely used for repairing railway tracks, by reduction of iron oxide to generate iron. This reduction is carried out by $$Al$$ powder.
Explanation:
The thermite process is the reaction of aluminum with iron oxide which forms elemental iron along with aluminum oxide.
In thermite reaction, $$Al$$ is the reducing agent.
As $$Al$$ is converting to $$Al_2O_3$$ so the oxidation state of $$Al$$ changes from $$0$$ to $$+3$$ in $$Al_2O_3$$ so it is the loss of electron that means oxidation takes place.
$$ Al \rightarrow Al^{3+} + 3 e^-$$
As a Reducing agent is the one that reduces itself that is why $$Al$$ acts as a reducing agent.
This reaction generates tremendous amounts of heat, which results in the melting of the railway tracks which are made of iron.
This can be used to repair and join the broken railway tracks.
Final answer: Option $$B$$
A compound added to lower the fusion temperature of the electrolytic bath in the extraction of Al is ___________.
Report Question
0%
cryolite and fluorspar
0%
Bauxite
0%
Iron and fluorspar
0%
none of these
Explanation
Pure alumina melts at about $$2000^oC$$ and is a bad conductor of electricity. If fused cryolite and fluorspar is added, the mixture melts at $$900^0C$$ and $$Al_2O_3$$ becomes a good conductor of electricity.
Which of the method used for the concentration of sulfide ores?
Report Question
0%
froth floatation
0%
smelting
0%
magnetic separation
0%
gravity separation
Explanation
This method
is
used
for those metals whose ore gets preferably wetted by the oil and the gangue by the water. The
sulphide ores
preferably wetted by the oil and the gangue with the water.
In thermite welding, to ignite the mixture we use :
Report Question
0%
magnesium ribbon
0%
potassium ribbon
0%
calcium ribbon
0%
manganese ribbon
Explanation
Thermite welding also known as exothermic welding and the reaction of metal oxide and aluminium powder reaches very high temperature. The activation energy for this reaction is very high and the initiation requires the use of a booster material such as powder magnesium metal.
Sketch shown is of an electrolytic cell used in the extraction of aluminium:
What is the substance of which the electrode A is made?
Report Question
0%
Graphite
0%
Diamond
0%
Iron
0%
Aluminium
Explanation
The diagram shows an aluminium oxide electrolysis cell. Both the negative electrode (cathode) and positive electrode (anode) are made of graphite, a form of carbon.
Report Question
0%
Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
0%
Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
0%
Assertion is correct but Reason is incorrect
0%
Both Assertion and Reason are incorrect
Explanation
Aluminium foil
(or
aluminum foil
) is aluminium
prepared in thin metal leaves
with a thickness less than 0.2 millimetres (8 mils); thinner gauges down to 6 micrometres (0.24 mils) are also commonly used.
Aluminium foil acts as a total barrier to light and oxygen (which cause fats to oxidise or become rancid), odours and flavours, moistness, and germs, and so it is used broadly in food and pharmaceutical packaging. The purpose of aluminium is to make long-life packs (aseptic packaging
) for drinks and dairy goods, which allows storing without refrigeration. Aluminium foil containers and trays are used to bake pies and to pack takeaway
meals, ready snacks and long lifepet
foods.
Gangue have :
Report Question
0%
sand and soil
0%
silt
0%
gravel
0%
all of these
Explanation
(i) Mineral is a naturally occurring substance that is solid and inorganic represented by chemical formula and has ordered structure. Minerals are differentiated based on their physical and chemical properties.
(ii) Ore is a type of rock that contains sufficient minerals with metals which are economically extracted by mining. Metal ores are generally oxides,sulphides,silicates. The ores are processed to extract metals.
(iii) Gangue are the impurities which are mixed closely with the ores. It is unwanted material which is of no market value and it is waste rock or mineral or sand etc.
The major step involved in extraction of a metal after its ore is :
Report Question
0%
concentration
0%
reduction
0%
purification
0%
all of these
Explanation
The three steps involved in extraction are:
1) Concentration of the ore to remove impurities.
2) Reduction of the ore to get the metal.
3) Purification of the ore.
The following question is relevant to the extraction of Aluminium:
Along with cryolite and alumina, another substance is added to the electrolyte mixture. the substance is ___________.
Report Question
0%
Fluorspar
0%
Mica
0%
NaCl
0%
None of these
Explanation
Fluorspar is the substance act as a solvent and it increases conductivity. (
Pure alumina melts at about $$2000^oC$$ and is a bad conductor of electricity. If fused cryolite and fluorspar is added, the mixture melts at $$900^oC$$ and $$Al_2O_3$$ becomes a good conductor of
electricity.)
Froth floatation process is used for the :
Report Question
0%
Oxide ores
0%
Sulphide ores
0%
Chloride ores
0%
All of these
Explanation
Froth floatation process is used for the sulphide ores.
In this method, wetting of the ore by an oil takes place.
A strong current of air is blown through the suspension, producing a heavy froth or foam on the surface. The metal sulphide is wetted by the oil but the gangues is not and the sulphide-oil mixture is carried to the surface by films of oil The froth is skimmed off, the gangue settles down on the bottom or remains underneath the froth.
Transmission wires are made of aluminium, since aluminium is:
Report Question
0%
Corrosive
0%
Resistant
0%
Good conductor of electricity
0%
Good conductor of heat
Explanation
Al is an active metal so its a good conductor of electricity and used in making of transmission wires.
If impurities can be oxidized more easily than the metal itself, which method is used?
Report Question
0%
Liquation method
0%
Distillation method
0%
Oxidation method
0%
None of these
Explanation
Oxidation process refers to a set of chemical treatment procedures designed to remove organic and inorganic materials in water and waste water by oxidation through reactions by hydroxyl ions.
Oxidation method is used when impurities are easily oxidisable. For example, lead as an impurity in silver is removed by heating, the impurity is easily oxidised to $$PbO$$ and removed by air.
Which metal is used for making foils used in packing of food materials?
Report Question
0%
Copper
0%
Platinum
0%
Aluminium
0%
Sodium
Explanation
Aluminium foils are used for preserving the food material and used as packaging material as it does not react with the food.It is white,soft and ductile metal. Aluminium is almost always alloyed which improves its mechanical properties when tempered.
Though aluminium is a reactive metal it is still used for packing food articles. Why?
Report Question
0%
Strong affinity of aluminium towards O$$_2$$
0%
Strong affinity of aluminium towards N$$_2$$
0%
Aluminium is a light metal
0%
None of the above
Explanation
Aluminium is used in packaging industry because it is a light metal.
Aluminium alloys are widely used in aircraft and ships because of :
Report Question
0%
their high melting point
0%
their hardness
0%
their high density
0%
their light weight
Explanation
Aluminium is ductile, malleable and lightweight, and has one third the density and stiffness of steel. It is easily machined, cast, drawn and extruded. Aluminium with magnesium alloy is used to make body of aircraft which is lightweight and resistant to corrosion.
Which of these is not the step involved in extraction of an ore?
Report Question
0%
Concentration of the ore.
0%
Electrolysis
0%
Reduction using carbon
0%
Corrosion
Explanation
The metals extracted from Earth's crust endure the process of concentration to remove impurities from the ore. Several processes, different for each metal like roasting and reduction are done to get the pure metal from it's combined state like sulphides or oxides. However, corrosion is not a step in the extraction of ore. Hence, Option $$D$$ is correct.
Stainless steel is very useful alloy in everyday life. In this alloy, the nickel is mixed with
Report Question
0%
Cu and Cr
0%
Fe and Cr
0%
Fe and Cu
0%
Fe and An
Aluminium is used in thermite welding because it :
Report Question
0%
is a light metal
0%
has more affinity for oxygen
0%
is a strong oxidising agent
0%
is a reactive metal
Explanation
Thermite is the trade name for one of the granular mixtures of aluminium metal and powdered ferric oxide as the chemical affinity of Al for oxygen is the basis of thermite process. Al is common because of its high boiling point and low cost. It is used in welding process to join railway tracks.
The composition of thermite mixture is :
Report Question
0%
iron (III) oxide and aluminium powder in the ratio 1:3
0%
aluminium powder and iron (III) oxide in the ratio 1:3
0%
aluminium powder and barium peroxide in the ratio 1:3
0%
barium peroxide and aluminium powder in the ratio 1:3
Explanation
Thermite mixture is a pyrotechnic composition of metal powder fuel and metal oxide. It has diverse composition including Aluminium because of its high boiling point and low cost. Oxidizers include iron(III) oxide. This mixture is used for thermite welding, often used to join rail tracks, metal refining, weapons, fireworks etc.
(a) Roasting and calcination are the two processes to reduce the metal oxides to the respective metals.
(b) Magnesium is extracted from its ore by electrolytic reduction process.
(c) Cryolite is used in metallurgy of aluminium in order to increase the fusibility and conductivity
(d) I Hall's process bauxite is leached with the help of $${Na}_{2}{CO}_{3}$$.
Which of the following options regarding the above statements is correct?
Report Question
0%
a, b and c
0%
b, c and d
0%
c and d
0%
only a
Explanation
(b) Magnesium is extracted from its ore by electrolytic reduction process.
(c) Cryolite is used in metallurgy of aluminium in order to increase the fusibility and conductivity
(d) I Hall's process bauxite is leached with the help of $${Na}_{2}{CO}_{3}$$. statements are correct. The concentrated ore is converted into metal oxide by calcination or roasting.
Which of the following is used in making planes?
Report Question
0%
Copper
0%
Tungsten
0%
Aluminium
0%
Steel
Explanation
Aluminium is most widely used in making planes. They have a low density and they do not corrode.
During electrolysis, electrons are being added directly to the metal ions at the ___________.
Report Question
0%
anode
0%
cathode
0%
both $$A$$ and $$B$$
0%
none of the above
Explanation
During electrolysis, electrons are being added directly to the metal ions at the cathode (the negative electrode). The downside (particularly in the aluminum case) is the cost of the electricity. An advantage is that it can produce very pure metals.
Process of removal of gangue from the ore are based on:
Report Question
0%
differences between physical and chemical properties of the gangue and the ore
0%
difference between densities of gangue and ore
0%
difference between melting point between of gangue and ore
0%
all of the above
Explanation
Impurities are removed prior to the extraction of metal. The process used for removal of gangue from the ore are based on the differences between physical and chemical properties of the gangue.
What will happen during roasting?
Report Question
0%
The sulphide ores are converted into oxides
0%
The oxide ores are converted into sulphides
0%
The sulphide ores are converted into carbonates
0%
The oxide ores are converted into carbonates.
Explanation
During roasting, the sulphide ores are converted into oxides by heating strongly in excess of air.
$$ZnS + 3O_2 \rightarrow 2ZnO + 2SO_2$$
Which if the following is a common reducing agent for extracting metals from ore?
Report Question
0%
$$CO$$
0%
Carbon
0%
Hydrogen
0%
All of the above
Explanation
Reduction is the process of removal of oxygen for extraction of metals from their oxide ores. The common reducing agents used for reduction of metal oxides are
:
Carbon monoxide, Carbon, Hydrogen.
Which metal foil is used for packing of some of the medicine tablets?
Report Question
0%
Copper
0%
Zinc
0%
Aluminium
0%
All of the above
Explanation
Aluminium is malleable. It can be beaten into thin sheets and can also be hammered into thin foils.
Metals more reactive than carbon are usually extracted by_________.
Report Question
0%
Pyrolysis
0%
Electrolysis
0%
Fractional distillation
0%
Filteration
Explanation
Metals more reactive than carbon are usually extracted by electrolysis. Electrolysis is the process of breaking down a compound using electrical energy and is needed to extract the most reactive metals.
Impurities found in ores are called:
Report Question
0%
mud
0%
gangue
0%
electrolyte
0%
none of the above
Explanation
Ores mine from the earth are usually contaminated with large amount of impurities such as soil, sand etc known as gangue.
0:0:1
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
0
Answered
0
Not Answered
0
Not Visited
Correct : 0
Incorrect : 0
Report Question
×
What's an issue?
Question is wrong
Answer is wrong
Other Reason
Want to elaborate a bit more? (optional)
Practice Class 12 Engineering Chemistry Quiz Questions and Answers
<
>
Support mcqexams.com by disabling your adblocker.
×
Please disable the adBlock and continue.
Thank you.
Reload page
