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Refining of metals - class-X

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Which of the following is not a method of refining of metals?

  1. Electrolysis

  2. Smelting

  3. Poling

  4. Liquation


Correct Option: B
Explanation:

Smelting is process in which metal is extracted from its ore by heating and melting. It is not a method of refining metal. Methods of refining metals are electrolysis poling, liquation, zone refining, vapour phase refining, distillation.

Which one of the following is the true in electrolytic refining?

  1. Impure metal is made cathode.

  2. Impure metals is made anode.

  3. Impure metals is made cathode and pure metal as anode.

  4. Both electrodes must be of pure metal.


Correct Option: B
Explanation:
  • In Electrolytic refining, the impure metal is made to act as an anode. A strip of the same metal in pure form is used as a cathode. 
  • They are put in a suitable electrolytic bath containing a soluble salt of the same metal. 
  • The more basic metal remains in the solution and the less basic ones go to the anode mud.
  • Zinc, copper is refined by this method.

Four metals and their methods of refinement are given
(i) $Ni,\ Cu,\ Zr,\  Ga$
(ii) Electrolysis, van Arkel process, zone refining, Mond's process
Choose the right method for each:

  1. $Ni:$ Electrolysis, $Cu:$ van Arkel process, $Zr:$ Zone refining, $Ga:$ Mond's process

  2. $Ni:$ Mond's process, $Cu:$ Electrolysis, $Zn:$ van Arkel process, $Ga:$ Zone refining

  3. $Ni:$ Mond's process, $Cu:$ van Arkel process, $Zr:$ Zone refining, $Ga:$ Electrolysis

  4. $Ni:$ Electrolysis, $Cu:$ Zone refining, $Zr:$ van Arkel process, $Ga:$ Mond's process


Correct Option: B
Explanation:

$Ni$ is refined by Mond's process.

$Cu$ is refined by Electrolysis.
$Zn$ is refined by Van Arkel process.
$Ga$ is refined by Zone refining.

Mark the correct statements:

(i) mercury can be refined by the process of distillation.

(ii) In poling, the molten impure metal is stirred with green poles of wood.

(iii) In electrolyte refining of metals, impure metal is made as cathode and a thin strip of pure metal is made as anode.

  1. (i) and (ii)

  2. (i) and (iii)

  3. (ii) and (iii)

  4. (i), (ii) and (iii)


Correct Option: A
Explanation:

Low boiling point metals like Mercury are purified with distillation.

Hence,  statement (i) is correct.
 
The heat of  copper makes the pole emit wood gas that reduces the cuprous oxide to copper.
In poling, the molten impure metal is stirred with green poles of wood.
Hence,option (ii) is correct.

In electrolyte refining of metals, impure metal is made as Anode  and a thin strip of pure metal is made as cathode.
Hence, option (iii) is incorrect.

Electrolysis is used for refining certain metals such as copper and zinc.

  1. True

  2. False


Correct Option: A
Explanation:

Electrolysis, process by which electric current is passed through a substance to effect a chemical change. The chemical change is one in which the substance loses or gains an electron (oxidation or reduction).

It is extensively used in metallurgical processes, such as in extraction (electrowinning) or purification (electrorefining) of metals from ores or compounds and in deposition of metals from solution (electroplating). Electrolysis of salt of copper and zinc results in the deposition of pure copper and zinc on cathode of the electrolytic cell.
option A is correct

'Softening of lead' means ___________.

  1. conversion of lead to $PbO$

  2. conversion of lead to $Pb _{3}O _{4}$

  3. removal of impurities(metallic) from lead

  4. washing lead with $HNO _{3}$ followed by alkali solution


Correct Option: C
Explanation:

The removal of  metallic impurities from lead is known as 'Softening of lead'.

In the electrolytic refining of a metal M, what would you take as the anode is : 

  1. impure metal M

  2. thin strip of pure metal M

  3. solution of salt of the metal M

  4. none of these


Correct Option: A
Explanation:

The purest copper is obtained by an electrolytic process using impure copper as the anode and a thin sheet of pure copper as cathode. The electrolyte is an acidic solution of copper sulphate. By passing electricity copper is dissolved from anode and deposits at cathode.

On the basis of following features identify the correct option:
I. This metal is not obtained in free state.
II. This metal is obtained by electrolysis of their chlorides in molten state.

  1. $Na$

  2. $Ca$

  3. both (1) and (2)

  4. neither (1) nor (2)


Correct Option: C
Explanation:

Both Sodium and calcium are highly reactive metal oxides are not reduced by carbon and these metals are obtained in free state by electrolytic reduction of their molten chloride salts.

In electrolytic refining, which one is the anode and which is cathode?

  1. Pure metal is the anode and impure metal is cathode

  2. Impure metal is made anode and pure metal cathode

  3. Both can be done interchangeably

  4. None of the above


Correct Option: B
Explanation:

In electrolytic refining, impure metal is made the anode and a thin strip of pure metal is made the cathode.

Why refining of metals is required?

  1. They are hard

  2. They are impure

  3. They are lustrous

  4. They are malleable


Correct Option: B
Explanation:

Refining of metals is required because the metals that have been extracted by concentration of ore are still impure.

Separation of impurities from the extracted metals is known as __________.

  1. distillation

  2. roasting

  3. calcination

  4. refining


Correct Option: D
Explanation:

Separation of impurities from the extracted metals is known as refining of metals.

Impurities present at anode are deposited at the bottom and called as _______.

  1. anode dust

  2. anode particulate

  3. anode mud

  4. anode impurities


Correct Option: C
Explanation:

In the electrolytic refining the process the impure sample is used as anode and pure metal is obtained at cathode. Impurities present at anode are deposited at the bottom and called as anode mud.

Refining of aluminium is done by __________.

  1. electrolysis

  2. distillation

  3. sedimentation

  4. oxidation


Correct Option: A
Explanation:

Refining of aluminium is done by electrolytic method. The aluminium obtained is 99.99% pure.

Which of the following is not a method of refining?

  1. Roasting

  2. Electrolysis

  3. Distillation

  4. Oxidation


Correct Option: A
Explanation:

Roasting is the method of converting the ore to its oxide form . It is not a method of refining.

When stones are separated from rice, we throw away the solid component.

  1. True

  2. False


Correct Option: A
Explanation:

When stones are separated from rice, we throw away the solid component. Stones are non useful whereas rice are useful. So we through away non useful solid and then we can have rice for cooking.

During extraction of metals, electrolytic refining is used to obtain pure metals. Material which will be used as anode, for refining of silver metal by this process, is:

  1. zinc

  2. impure silver

  3. pure silver

  4. iron


Correct Option: B
Explanation:

Electrolysis is the dissolving of metal from one electrode of an electrolytic cell to another electrode in pure form. It gives the highest purity metal product. The impure silver is cast into a slab which is the anode, while pure silver sheet metal is the cathode.

Sodium is obtained by the electrolysis of:

  1. an aqueous solution of sodium chloride

  2. an aqueous solution of sodium hydroxide

  3. fused sodium chloride

  4. fused sodium sulphate


Correct Option: C
Explanation:

Sodium is obtained by the electrolysis of fused mixture of $NaCl$ and $CaCl _2$ (Down's process). Reaction can be written as:

$2NaCl \rightarrow 2Na + {Cl} _2$


last process of metallurgy is ?

  1. Refining

  2. Concentration

  3. Reduction

  4. Smelting


Correct Option: A
Explanation:

After extraction and separation, refining is the last process of Metallurgy. It involves the refining of pure metal finally. 

Which of the following pair can be refined using same basic principle?

  1. $Cu$ and $Ag$

  2. $Si$ and $Ge$

  3. $Ti$ and $Ni$

  4. All of these


Correct Option: A

In the refining of copper, pure copper is deposited on:

  1. Anode

  2. Cathode

  3. 1 and 2 both

  4. None of these


Correct Option: B
Explanation:

In electrorefining step, impurities like Fe, Ni, Zn get dissolved in the solution while Au, Ag and Pt are deposited as anode mud below the anode and pure copper deposited at cathode.

Zirconium is purified by 

  1. Liquidation

  2. Electrolytic process

  3. Van Arkel method

  4. Calcination


Correct Option: C

(a) Mond process       (1) Ni
(b) Van-Arkel              (2) Zr
(c) Liquation               (3) Ga
(d)Zone refining         (4) Sn
Correct option is:

  1. $a-(1)$ $ b-(2)$ $c-(2)$ $d-(4)$

  2. $a-(1)$ $b-(2) $ $c-(4)$ $d-(3)$

  3. $a-(3)$ $b-(2)$ $c-(4)$ $d-(1)$

  4. $a-(2)$ $b-(3)$ $c-(4)$ $d-(1)$


Correct Option: B
Explanation:
Solution:- (B) $a-(1)$ $b-(2) $ $c-(4)$ $d-(3)$
(a) Mond process     $ \Rightarrow$ Ni
(b) Van-Arkel            $ \Rightarrow$ Zr
(c) Liquation             $ \Rightarrow$ Sn
(d)Zone refining       $ \Rightarrow$ Ga

An insoluble substance or mixture that collects at the anode in an electrolytic refining or plating process is known as anode mud.

State True or False.

  1. True

  2. False

  3. Cannot be determined

  4. None of the above


Correct Option: A
Explanation:

Anode mud is the insoluble impurity which settles down at the bottom of the anode during electrolytic refining. The soluble impurities go into the solution.

So the given statement is correct
Hence option $A$ is correct.

Gold is extracted by hydrometallurgical process, based on its property:

  1. of being electropositive

  2. of being less reactive

  3. to form complex which are water soluble

  4. to form salt which are water soluble


Correct Option: C
Explanation:
Hydrometallurgy is a method for obtaining metals from their ores. It is a technique within the field of extractive metallurgy involving the use of aqueous chemistry for the recovery of metals from ores, concentrates, and recycled or residual materials. Gold is extracted by hydrometallurgical process, based on its property to form complexes which are water soluble.

$4Au(s)+8CN^- +O _2(g)+2H _2O\rightarrow \underset{soluble \, complex}{4[Au(CN) _2]^-} + 4OH^-$

Which of the following is true for electrolytic refining?

  1. Pure metal is anode and impure metal is cathode

  2. Pure metal is cathode and impure metal is anode

  3. Both are anode

  4. Both are cathode


Correct Option: B
Explanation:
In Electrolytic refining, the impure metal is made to act as an anode. A strip of the same metal in pure form is used as a cathode. 
They are put in a suitable electrolytic bath containing a soluble salt of the same metal. 
The more basic metal remains in the solution and the less basic ones go to the anode mud.
Zinc, copper is refined by this method.

The method used in metallurgy to refine the impure metal is:

  1. Mond process

  2. Van Arkel process

  3. Liquation

  4. All of the above


Correct Option: D
Explanation:
$\text{Mond Method:}$ It is specially used for Ni. The vapour phase refining of Ni on heating in a stream of CO forms volatile $Ni(CO) _4$. These vapours when subjected to still higher temperature, decompose to give pure metal.

$\text{Liquation Method:}$ Pb, Sn, Bi, Zn etc are purified by this method. The metal has a low melting point and impurities have a high melting point. In an open hearth, the metal is heated to its melting point and metal melts down and impurities remain behind.

$\text{Van Arkel method}$: This method is used for ultrapure metals like Ti, Zr etc. The metal is converted into its volatile stable compound such as $TiI _4$, leaving behind impurities. The stable volatile compound thus formed is decomposed to get the pure metal.

Hence, option D is correct.

Select the incorrect meaning of softening of lead.

  1. melting pure lead at high temperature

  2. removal of impurities, except silver, present in commerical lead

  3. formation of lead alloy

  4. formation of 100% pure lead


Correct Option: A,C,D

Silver containing lead as an impurity is not purified by:

  1. Poling

  2. Cupellation

  3. Levigation

  4. Distillation


Correct Option: A,C,D
Explanation:

Poling is a method employed in the purification of copper which contains cuprous oxide as an impurity. Silver containing lead as an impurity is not purified by polling.


Cupellation is a refining process in metallurgy, where ores or alloyed metals are treated under high temperatures and controlled operations to separate noble metals like gold and silver from base metals like lead, copper, zinc, arsenic or bismuth, present in the ore.

Levigation: The process of removal of heavy ore particles from lighter particles by washing with water. Silver containing lead as an impurity is not purified by levigation.in this process heavy ore particles are removed from a lighter particle. but not lighter particles from heavy particles.

Distillation is a process of separating the component substances from a liquid mixture by selective evaporation and condensation. Distillation may result in essentially complete separation (nearly pure components), or it may be a partial separation that increases the concentration of selected components of the mixture. Ex: zinc and mercury are distilled by a fractional distillation process.

So, silver-containing lead as an impurity is not purified by polling, levigation & distillation.

Hence options A, C, D are correct.

Which of the following metals are obtained by electrolysis of their chlorides in molten state?
(i)   $Na$
(ii)  $Ca$
(iii) $Fe$
(iv) $Cu$

  1. (i) and (iv)

  2. (iii) and (iv)

  3. (i) and (iii)

  4. (i) and (ii)


Correct Option: D
Explanation:

Sodium and calcium are the metals obtained by electrolysis of their chlorides in molten state. Both are reactive metals.

In the electrolytic refining of zinc,

  1. graphite is at the anode

  2. the impure metal is at the cathode

  3. the metal ions gets reduces at the anode

  4. acidified zinc sulphate is the electrolyte


Correct Option: D
Explanation:

In the electrolytic refining of zinc

Anode → impure zinc

Cathode → strip of pure zinc

Electrolyte → acidified zinc sulphate solution

At anode → Oxidation of metal

                     (i.e., $Zn \longrightarrow Zn^{2+} + 2e^–$)

                            (impure)

At cathode → reduction of metal ions

                       (i.e., $Zn^{2+} + 2e^– \longrightarrow Zn$)

                          (Form solution)    (pure)

Aluminium is purified by :

  1. roasting

  2. sublimation

  3. electrolytic refining

  4. reduction with carbon


Correct Option: C
Explanation:

Aluminium is purified by electrolytic reduction. Aluminium lies on the top of electrochemical series therefore it is purified by electrolytic refining.

Anode mud is obtained in which of the following processes?

  1. Roasting

  2. Zone refining

  3. Electrolytic refining

  4. Calcination


Correct Option: C
Explanation:

Metals such as Cu, Ag, Zn, Sn, Pb, Al, Ni, Cr are refined by electrolytic refining method. The impure metal is made the anode of a electrolytic cell, while cathode is thin plate of pure metal. Electrolyte is the solution of a double salt of the metal. On passing the electric current pure metal from the anode dissolves and gets deposited at the cathode. The soluble impurities go into the solution while insoluble or less electropositive impurities settle down below the anode as anode mud or sludge. 

Which of the following metal refined-electrolytically?

  1. $Al$

  2. $Na$

  3. $Cu$

  4. $Fe$


Correct Option: A,C
Explanation:

The impure copper from a smelter is cast into a block to form the positive anode and the cathode is made up of purified copper. These are dipped into an electrolyte of copper sulphate solution. purification of aluminium can be carried out by the Hoopes process. This is an electrolytic process.

Which of the following metals is not refined by electrolytic refining?

  1. $Na$

  2. $Au$

  3. $Cu$

  4. $Al$


Correct Option: A
Explanation:

The sodium and chloride produced in the electrolysis are kept from coming in contact with each other as the sodium is highly reactive and it must be prevented from coming in contact with oxygen as the metal quickly oxidizes under high temperature conditions.

The metal refined-electolytically is:

  1. $Al$

  2. $Na$

  3. $Cu$

  4. $Fe$


Correct Option: C
Explanation:

Copper and zinc will be refined in electrolytic refining process for the following reasons.

$\rightarrow$ It meets the cost of refining 
$\rightarrow$ In more cases, electrolyte is selected which is the sulphate of the metal that is going to be refined. 

Which of the following is purification method?

  1. Distillation

  2. Electrolytic process

  3. Filtration

  4. All of the above


Correct Option: D
Explanation:
Purification is the physical separation of a chemical substance of interest from foreign or contaminating substances e.g. Filtration, centrifugation, evaporation, liquation, crystallization, adsorption, smelting, refining, distillation, fractionation, electrolysis, sublimation.

Mark the correct option:
a) Pure metal from the electrolyte is deposited at the anode.
b) The soluble impurities go into the solution.
c) Insoluble impurities known as anode mud.

  1. a, b

  2. b, c

  3. a, c

  4. All of the above


Correct Option: B
Explanation:

On passing the current through the electrolyte, pure metal from the anode dissolves into the electrolyte. An equivalent amount of pure metal from electrolyte is deposited on the cathode.

In electrolytic refining, which of the following is used as an electrolyte?

  1. Impure metal

  2. Pure metal

  3. Metal salt

  4. None of the above


Correct Option: C
Explanation:

A solution of the metal salt is used as an electrolyte. Impute metal is made the anode and a thin strip of pure metal is made of cathode.

Separation of impurities from the extracted metals is generally done by __________.

  1. distillation

  2. sedimentation

  3. electrolysis

  4. none of the above


Correct Option: C
Explanation:

Separation of impurities from the extracted metals is generally done by electrolysis of impure metals.

Lead is refined by _________________.

  1. electrolysis

  2. distillation

  3. oxidation

  4. none of the above


Correct Option: A
Explanation:

Lead is refined by electrolytic method. The other metals which are also refined by this method are aluminium and copper.

Sodium metal is refined by ___________.

  1. distillation

  2. electrolysis

  3. both $A$ and $B$

  4. none of the above


Correct Option: B
Explanation:

Sodium metal is refined by electrolytic method. 

The impurities obtained after extraction of iron by reduction is called as _______.

  1. mud iron

  2. pig iron

  3. dirt iron

  4. impure iron


Correct Option: B
Explanation:

Iron obtained after extraction by reduction contains 34% carbon and other impurities like phosphorus, manganese etc. This is called as pig iron.

By heating pig iron in furnace it is converted to ____________.

  1. wrought iron

  2. impure iron

  3. carbon iron

  4. none of the above


Correct Option: A
Explanation:

By heating pig iron in furnace it is converted to wrought iron. It is the pure form of iron which contains carbon. It is soft, grey, tough, malleable and ductile.

Refining of metal is:

  1. purification of metal

  2. concentration of metal

  3. conversion into oxides

  4. none of above


Correct Option: A
Explanation:

Refining consists of purifying an impure material, in this case, a metal. It is to be distinguished from other processes such as smelting and calcining in that those two involve a chemical change to the raw material, whereas in refining, the final material is usually identical chemically to the original one, only it is purer.

The electrolyte used for copper refining is an acidic solution of:

  1. copper chloride

  2. copper sulphide

  3. copper sulphate

  4. impure copper


Correct Option: C
Explanation:

The purest copper is obtained by an electrolytic process, undertaken using a slab of impure copper as the anode and a thin sheet of pure copper as the cathode. The electrolyte is an acidic solution of copper sulphate. 

The purest copper is obtained by:

  1. concentration process

  2. electrolytic refining

  3. pyrolysis

  4. crystallization


Correct Option: B
Explanation:

The purest copper is obtained by an electrolytic process, undertaken using a slab of impure copper as the anode and a thin sheet of pure copper as the cathode.

For alkali metals, only electrolytic reduction is employed.

  1. True

  2. False


Correct Option: A
Explanation:

Definition of electrolytic reduction: Removal of oxygen (or decrease of its active valency in the case of a positive element) by electrical means.

The highly electropositive metals, such as the alkali and alkaline earth metals are isolated by electrolytic reduction of their fused halides, since no suitable chemical reducing agent is available and aqueous solutions could not be used due to reactive nature of these metals.
For alkali metals, only electrolytic reduction is employed.

Match the following.

Separation process Purpose for which we do the separation What do we do with the separated components
1) Separate stones from rice a) To remove non useful components i) We throw away the impurities
2) Churning milk to obtain butter b) To remove impurities or harmful components ii) we throw away the solid component
3) Separate tea leaves c) to separate two different but useful components. iii) we use both the components.


  1. 1) c) ii)

    2) a) i)

    3) b) iii)

  2. 1) c) ii)

    2) b) i)

    3) a) iii)

  3. 1) c) ii)

    2) a) iii)

    3) b) i)

  4. 1) a) ii)

    2) c) i)

    3) b) iii)


Correct Option: A
Explanation:
Separation process Purpose for which we do the separation What do we do with the separated components
1) Separate stones from rice c) to separate two different but useful components. ii) we throw away the solid component
2) Churning milk to obtain butter a) To remove non useful components i) We throw away the impurities
3) Separate tea leaves b) To remove impurities or harmful components iii) we use both the components.


Which of the following represents correct statement(s)?

  1. The method of handpicking can be used for separating slightly larger sized impurities like the pieces of dirt, stone and husk from wheat, rice or pulses.

  2. The quantity of such impurities is usually very large.

  3. In such situations, we find that handpicking is not a convenient method of separating substances.

  4. All of the above


Correct Option: A
Explanation:

The statement (A) represents correct statement.
The method of handpicking can be used for separating slightly larger sized impurities like the pieces of dirt, stone and husk from wheat, rice or pulses.
The quantity of such impurities is usually not very large.
In such situations, we find that handpicking is a convenient method of separating substances.

Handpicking is used for separating tiny impurities.

  1. True

  2. False


Correct Option: B
Explanation:

Handpicking is used for separating slightly larger sized impurities like the pieces of dirt, stone, and husk from wheat, rice or pulses.

Which of the following represents incorrect statement(s)?

  1. The process that is used to separate grain from stalks is winnowing.

  2. In this process, the grain seeds are beaten to free the stalks.

  3. Threshing is not done with the help of bullocks. Machines are used to thresh even small quantities of grains.

  4. All of the above


Correct Option: D
Explanation:

All of the given options represents incorrect statements.
The process that is used to separate grain from stalks is threshing. In this process, the stalks are beaten to free the grain seeds.
Threshing is done with the help of bullocks. Machines are also used to thresh large quantities of grains.

Which of the following represents correct statement(s)?

  1. Ginning was traditionally done by machines.

  2. These days, ginning is also done by hand.

  3. Both of the above.

  4. None of the above.


Correct Option: D
Explanation:

Ginning was traditionally done by hand. These days, machines are also used for ginning.
Note:The ginning of cotton is the process of separation of fibres from the seeds by combing.
From the bolls, cotton is usually picked by hand. Fibres are then separated from the seeds by combing. This process is called ginning of cotton.

Sieves are used at construction sites to separate pebbles and stones from sand.

  1. True

  2. False


Correct Option: A
Explanation:

Sieves are used at construction sites to separate pebbles and stones from sand. Sieves are also used to separate fine flour particles from the bigger impurities.

Nickel metal is purified by the vapour phase refining process. This process is based on the fact that:

  1. nickel metal sublimes at high temperature

  2. nickel reacts with carbon monoxide to form nickel carbonyl which decomposes at high temperature to form nickel

  3. nickel reacts with chlorine to form nickel chloride which is volatile and decomposes easily to nickel

  4. nickel can be vapourized under vacuum leaving behind impurities


Correct Option: B
Explanation:

Nickel metal is purified by the vapour phase refining process. This process is based on the fact that nickel reacts with carbon monoxide to form highly volatile nickel tetracarbonyl which decomposes at high temperature to form pure nickel metal.
 $\displaystyle Ni+4CO \xrightarrow {\text {330-350 K}} Ni(CO) _4$
 $\displaystyle Ni(CO) _4 \xrightarrow { \text {450-470 K}}  \underset {\text {Pure metal }}{Ni}+ 4 CO$

Group II. A elements are extracted from their chlorides by..........reduction.

  1. Magnetic

  2. Static

  3. Electrolytic

  4. Dymanic


Correct Option: C
Explanation:

Because of their electronegativity of the chlorine atom in their ores, the electronic influence is more. So, they are extracted by electrolytic reduction

Which of the following statements is/are correct regarding metallurgy?

  1. Both calcination and roasting are generally carried out in the same furnace, i.e., reverberatory furnace.

  2. The slag formed during the extraction of Copper metal from Chalcopyrites ore is $CaSiO _3$.

  3. Mond's process involved in the extraction of nickel is related with formation and decomposition of a square planner complex of nickel metal.

  4. In case of electrolytic refining of extracted metals, generally impure metal rod is made the anode and pure metal rod is made the cathode.


Correct Option: A,D
Explanation:

Both calcination and roasting are generally carried out in the this furnace, one in absence of air and other in presence of air.
The slag formed during the extraction of Copper metal from Chalcopyrites ore is $FeSiO _3$.
Mond's process involved in the extraction of Nickel is related with formation and decomposition of a tetrahedral complex of nickel metal $[Ni(CO) _4]$. 

In case of electrolytic refining of extracted metals, generally impure metal rod is made the anode and pure metal rod is made the cathode. This is evident as at anode, we get impure slag and at cathode, we get pure metal.

Silver can be separated from lead by:

  1. Distillation

  2. Amalgamation

  3. Filtration

  4. Cupellation


Correct Option: D
Explanation:

Cupellation is a process where ores are treated under high temperatures and controlled operations to separate noble metals like gold and silver from base metals like lead, copper, zinc, and others present in the ore or alloyed metal.

Refining of silver is done by___________.

  1. liquidation

  2. poling

  3. cupellation

  4. van Arkel method


Correct Option: C
Explanation:

Cupellation is a process where ores are treated under high temperatures and controlled operations to separate noble metals like gold and silver, from base metals like led, copper, zinc, and others present in the ore or alloyed metal.

Refining of silver is done by________.

  1. liquidation

  2. Poling

  3. cupellation

  4. van Aekel method


Correct Option: C
Explanation:

Cupellation is a process where ores are treated under high temperatures and controlled operations to separate noble metals like gold and silver, from base metals like led, copper, zinc, and others present in the ore or alloyed metal.

Cupellation process is used in the metallurgy of:

  1. Copper

  2. Silver

  3. Aluminium

  4. Iron


Correct Option: B
Explanation:

Cupellation is a process where ores are treated under high temperatures and controlled operations to separate noble metals like gold and silver, from base metals like led, copper, zinc, and others present in the ore or alloyed metal.

When alloy of silver and lead is rich in silver:

  1. Cupellation process is used

  2. Parke's method is used

  3. Pattinson's method is used

  4. Any of the above methods can be used


Correct Option: A
Explanation:

When alloy of silver and lead is rich in silver, cupellation process is used.
The silver metal can be obtained in when alloy of silver and lead is rich in lead is:
i) Parke's process
ii) Pattinson's process

Softening of lead means:

  1. Melting pure lead at high temperature

  2. Removal of impurities, except silver, present in commercial lead

  3. Formation of lead alloy

  4. Formation of 100% pure lead


Correct Option: B
Explanation:

We know the melting point of pure lead is very high. Softening of lead means removal of metallic impurities, except silver, present in the commercial lead. 


B  is the correct answer

Tin is not refined by:

  1. Liquidation

  2. Zone refining

  3. Poling

  4. None of the above


Correct Option: B
Explanation:
Poling is a [metallurgical] method employed in the purification of copper which contains copper oxide as an impurity and also in the purification of tin ("Sn") which contains tin oxide (stannic oxide or "$SnO _2$") as an impurity. It was the use of these greenwood poles gave rise to the term "poling."

Liquidation is suitable for metals with low melting points for example, tin. In this process, we heat the impure metal and then we let it flow on a sloped surface. The impurities will remain behind and the pure metal will collect at the bottom of the slope.


Zone refining is a special method we use to purify metals. It was the invention of William Pfann. It purifies metals to a very high degree. A rod of impure metal is placed in a container which we fill with inert gas. Then we place a circular heater around the rod at the top.

The melting point of tin is low. So zone refining is not suitable for Tin.

Hence, option B is correct.

When alloy of silver and lead is rich in silver :

  1. CupelIation process is used

  2. Parke's method is used

  3. Bett's method is used

  4. All of the above method


Correct Option: A
Explanation:
Cupellation: Pb impurities present in Ag are removed by this method. The impure metal is heated in a cupel or oval shaped crucible made of bone ash or cement and blast of air is passed over the molten mass. The impurities get oxidised and removed with the blast of air.

Refining of tin can be done by :

  1. cupellation

  2. liquation

  3. poling

  4. electrorefining


Correct Option: B,C,D
Explanation:
Poling is a method employed in the purification of copper which contains copper oxide as an impurity and also in the purification of tin ("Sn") which contains tin oxide (stannic oxide or "SnO2") as an impurity. It was the use of these greenwood poles gave rise to the term "poling."

Liquation is suitable for metals with low melting points, for example, tin. In this process, we heat the impure metal and then we let it flow on a sloped surface. The impurities will remain behind and the pure metal will collect at the bottom of the slope.

Electrorefining, producing pure tin from waste materials in cheap acid electrolytes can be effectively operated with parameters set to provide for the stability of the solution and high current efficiencies and the use of the periodical current reversal (PCR) technique.

Cupellation is a refining process in metallurgy where ores or alloyed metals are treated under very high temperatures and have controlled operations to separate noble metals, like gold and silver, from base metals, like lead, copper, zinc, arsenic, antimony, or bismuth, present in the ore.

Cupellation is used for purifying of metal under high temperature. so it is not suitable for tin(low melting point metal).

Extraction of metal from the ore cassiterite involves

  1. carbon reduction of an oxide ore

  2. self- reduction of an sulphide ore

  3. removal of iron impurity

  4. both A and C


Correct Option: D
Explanation:

Tin is obtained by reducing the ore cassiterite with coal in a reverberatory furnace; limestone is added to produce a slag with impurities, which can be removed.

$SnO _2  +  2C \longrightarrow Sn + 2 CO$.

Crude tin so obtained is contaminated with iron, lead, and other metals. It is, therefore, remelted on an inclined furnace. The process is called liquation. The easily fusible tin metals away and the less fusible impurities are left behind. Molten tin is finally stirred with green poles of wood in contact with air. In this process, any remaining metal impurities are oxidized forming a scum, which rises to the surface and is removed. This process is called polling.

Which are correctly matched?

  1. Poling-refining of copper

  2. Cupellation- refining of silver

  3. Smelting-An oxidation process

  4. Roasting-An oxidation process


Correct Option: A,B,D
Explanation:

A) Poling is a method employed in the purification of copper which contains cuprous oxide as an impurity.correct.
B) Cupellation is a refining process in metallurgy, where ores or alloyed metals are treated under high temperatures and controlled operations to separate gold and silver, from lead, copper, zinc, arsenic, antimony or bismuth.correct.
C) The process of extracting a metal from its oxide is known as 'smelting'. Most smelting processes involve direct reduction of the ore by carbon to metal and carbon dioxide. The production of primary aluminium is a good example of such a process. Its not oxidation.wrong
D) Roasting is a step of the processing of certain ores More specifically, roasting is a metallurgical process involving gassolid reactions at elevated temperatures with the goal of purifying the metal component(s). During roasting, the sulfide is converted to an oxide, and sulfur is released as sulfurdioxide, a gas.$2Cu _2S + 3O _2\rightarrow  2 Cu _2O + 2 SO _2$.correct.
options A,B & D are correct.

In Poling process, Hydrocarbon gases escaping from the poles act as _____ agents.

  1. reducing

  2. oxidation

  3. both

  4. none


Correct Option: A
Explanation:

Poling is a process in which the impure metal containing oxide as impurities is purified. It is melted and stirred with green poles of wood. Hydrocarbon gases escaping from the poles act as reducing agents and reduce the oxide impurities e.g., impurity of Cu$ _2$O which is reduced to metallic copper by poling.
$Cu _2O + CO \rightarrow 2Cu + CO _2 \uparrow$
$Cu _2O + H _2 \rightarrow 2Cu + H _2O$

In polling, wood gas is responsible for the removal of volatile impurities.

  1. True

  2. False


Correct Option: A
Explanation:

True. Polling is used for converting Copper Oxide $(Cu _2O)$ to Copper $(Cu)$. When ore is heated with wood poles, the poles release charcoal, shoot and gas. The gas released reduces $CuO$ to $Cu$. So the gas takes away impurities. 

Which of the following methods is used to remove lead present in silver ?

  1. Cupellation

  2. Distillation

  3. Poling

  4. Lavigation


Correct Option: A
Explanation:

Cupellation is a process of separation of gold or silver from impurities by melting the impure metal in a cupel (a flat porous dish made of refractory or high-temperature resistant material  ) and then directing a blast of hot air on it in a special furnace. The impurities, including lead,copper, tin, and other unwanted metals, are oxidized and partly vaporized and partly absorbed into the pores of the cupel.

Poling process:

  1. reduces $SnO _2$ to Sn

  2. oxidizes impurities like iron and removes as scum

  3. uses green poles

  4. uses brown poles


Correct Option: A,B,C
Explanation:

Poling: A refining process of crude metal for removing metal oxide impurities by stirring molten metal in a ladle with a pole of green wood (poles).


In the poling process, the reduction of oxides to metal atom will be done.

Ex: Extraction of copper from copper oxide and Sn from $SnO _2$.

Hence options A,B & C are correct.

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