Tag: basics of metallurgy

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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.

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

During melting of ice, the temperature of the ice does not change until the ice melts. The heat is used up in :

  1. changing the state overcoming the forces of attraction

  2. changing the state without overcoming the forces of attraction

  3. releasing into atmosphere

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The heat is used up in changing the state overcoming the forces of attraction.

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

Prior to reduction, metal sulphide and carbonates are converted into oxides because:

  1. carbonates, sulphides are heavy molecules

  2. it is easier to obtain a metal from its oxide as compared to its sulphides and carbonates

  3. it is easy to heat oxide compared to sulphides and carbonates
  4. both $A$ and $B$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

It is easier to obtain a metal from its oxide, as compared to its sulphides and carbonates. Therefore, prior to reduction, the metal sulphides and carbonates must be converted to metal oxides.