Tag: extraction of metals from ore

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Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

Lead obtained from galena ore (PbS) by air reduction or carbon reduction process contains base metal (Cu, Bi, As, Sn, Zn) as impurities. Gelatin acts as an addition agent in the electrolysis of Pb. In the presence of gelatin, Pb becomes :

  1. hard and brittle

  2. soft and rubbery

  3. smooth and uniform

  4. only brittle
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Lead obtained contains impurities like $Cu, Sb, Sn, As, Ag, Au, etc.$ which make it hard. During electrolytic refining of lead, the electrolyte $(PbSiF _6+H _2SiF _6)$ is mixed with a little gelatin. Gelatin is added for smooth and uniform deposition of lead in this process. 

Hence, the correct option is (C).
Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

Which of the following metal oxides are reduced by self reduction method?

  1. $Cu _2O$
  2. $PbO$
  3. $HgO$
  4. $CaO$
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

Self-reduction process:  This process is also called auto reduction process or air reduction process. 


The sulphide ores of less electropositive metals like Hg, Pb, Cu etc. are heated in the air as to convert part of the ore into oxide or sulphate which then reacts with the remaining sulphide ore to give the metal and sulphur dioxide. 


No external reducing agent is used in this process.

Hence options A,B & C are correct options.
Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

Pb is a very important element of carbon family. It forms a number of compounds which are very useful in industries. The process of removal of base metals (Cu, Sn, Bi, As) from lead is called:

  1. softening process

  2. liquation

  3. parke's process

  4. cupellalion
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For the removal of base metals the impure bullion is charged to a softening furnace whereby oxidation these elements form drosses or slags and, with some lead, are skimmed from the bath. This is the softening process. 

Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

The main source of lead is PbS. It is converted to Pb by:- 


(i) ${PbS\xrightarrow[\Delta]{air }PbO+SO _2\xrightarrow[\Delta]{C}Pb+CO _2}$


(ii) ${PbS\xrightarrow[\Delta]{air }PbO+PbS\xrightarrow[]{\Delta}Pb+SO _2}$ 

Self reduction process is:

  1. i

  2. ii

  3. both

  4. none
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Self reduction process of Pb is

$PbS + 2PbO \rightarrow   3Pb + SO _2$
so (ii) is self reduction process.

Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

Which of the following reduction processes are correct?

  1. ${Fe _2O _3+C\overset{Reduction}{\rightarrow}Fe}$
  2. ${ZnO+C\overset{Reduction}{\rightarrow}Zn}$
  3. ${SnO _2+C\overset{Reduction}{\rightarrow}Sn}$
  4. ${PbO+C\overset{Reduction}{\rightarrow}Pb}$
Reveal answer Fill a bubble to check yourself
A,B,C,D Correct answer
Explanation

Reduction is loss of oxygens.
In all the above reactions the metal oxides are reduced to metals by the elimination of oxygens,so all are reduction ractions.
Hence options A,B,C & D are correct.

Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

Which one of the following metals can not be extracted by using Al as a reducing agent ________________.

  1. $\displaystyle Na$ from $\displaystyle { Na } _{ 2 }O$
  2. $\displaystyle Cr$ from $\displaystyle { Cr } _{ 2 }{ O } _{ 3 }$
  3. $\displaystyle Mn$ from $\displaystyle { MnO } _{ 2 }$
  4. $\displaystyle Fe$ from $\displaystyle { Fe } _{ 2 }{ O } _{ 3 }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

As sodium  (alkali metal) is more reactive than Al so it cannot be extracted from $Na _2O$ by using Al as a reducing agent.

Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

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.

  1. e c b d a

  2. c e b d a

  3. c e b a d

  4. c e d b a
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

(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
(e) Dressed ore is required for it to be concentrated.
(b) The ore should be converted to its oxide form.
(d) The ore in the form of oxide is required to be reduced.
(a) The metal obtained from its oxide require further purification for end use.