We all know that salt can be extracted from seawater, but one element can also be extracted from seawater. Do you know what that is? It's gold! Although present in trace amounts, gold is naturally found in ocean water, but since its extraction is very costly, it is not practised often. NCERT Exemplar Class 12 Chemistry Chapter 6 Principles and Processes of isolation of elements talks about the various methods of extraction and metallurgical processes used to extract metals from their natural sources.
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The NCERT Exemplar Class 12 Chemistry Solutions contains questions from every topic with detailed explanations. These NCERT exemplar solutions will help students grasp complex extraction methods and will also improve their problem-solving speed. In this article, the higher-order thinking skill (HOTS) questions are also included to enhance your critical thinking. We have also added some points that will help students build a good strategy to solve the questions. Students can also refer to NCERT Solutions for additional practice and conceptual clarity.
At first, the MCQ questions are covered in the Class 12 Chemistry NCERT Exemplar Solutions Chapter 6 to enhance your knowledge. The concepts are explained in detail in notes available on our website
Question 1. In the extraction of chlorine by electrolysis of brine ____________.
(i) oxidation of $\text {Cl}^{-}$ ion to chlorine gas occurs.
(ii) reduction of $\text {Cl}^{-}$ ion to chlorine gas occurs.
(iii) For the overall reaction, $\Delta \text {G}^{\ominus }$ has a negative value.
(iv) A displacement reaction takes place.
Answer:
The answer is option (i).
The oxidation reaction of $\text {Cl}^{-}$ ion is responsible for the extraction of chlorine from brine
$2H_{2}O(l)+2Cl^{-}(aq)\rightarrow H_{2}(g)+Cl_{2}(g)+2OH^{-}(aq)$
The $\Delta G^{0}$ for this reaction is $+422\; kJ$
$\Delta G^{0}=-nFE^{0}$
$E^{0}=\frac{\Delta G^{0}}{nF}=-2.2 V$
Question 2. When copper ore is mixed with silica, in a reverberatory furnace copper matte is produced. The copper matte contains ____________.
(i) sulphides of copper (II) and iron (II)
(ii) sulphides of copper (II) and iron (III)
(iii) sulphides of copper (I) and iron (II)
(iv) sulphides of copper (I) and iron (III)
Answer:
The answer is option (iii).
On mixing copper ore with silica in a reverberatory furnace, iron silicate comes off as slag producing copper in the form of copper matte containing copper sulphide $[Cu_{2}S(I)]$ and some iron sulphide $[FeS(II)].$
Question 3. Which of the following reactions is an example of autoreduction ?
(i) $\text {Fe}_{3}\text {O}_{4}+\text {4CO}\rightarrow \text {3Fe}+\text {4CO}_{2}$
(ii) $\text {Cu}_{2}\text {O}+\text {C}\rightarrow \text {2Cu}+\text {CO}$
(iii) $\text {Cu}^{2+}(aq)+Fe (s)\rightarrow \text {Cu (s)}+Fe^{2+}(aq)$
(iv) $\text {Cu}_{2}\text {O}+\frac{1}{2}\text {Cu}_{2}\text {S}\rightarrow \text {3Cu }+\frac{1}{2}\text {SO}_{2}$
Answer:
$\text {Cu}_{2}\text {O}+\frac{1}{2}\text {Cu}_{2}\text {S}\rightarrow \text {3Cu }+\frac{1}{2}\text {SO}_{2}$
In this reaction reduction of copper (I) oxide by copper (I) sulphide takes place. Since, copper is reduced by itself, this process is known as auto-reduction and the solidified copper so, obtained is known as blister copper. We get the copper metal on reaction of sulphide ore of copper with its oxide.
Question 4. A number of elements are available in earth’s crust but most abundant elements are ____________.
(i) $\text {Al and Fe}$
(ii) $\text {Al and Cu}$
(iii) $\text {Fe and Cu}$
(iv) $\text {Cu and Ag}$
Answer:
The answer is option (i).
Several elements are available in the earth’s crust but the most abundant elements in the earth’s crust include $\text {Al and Fe}$.
Question 5. Zone refining is based on the principle that ___________.
(i) Impurities of low-boiling metals can be separated by distillation.
(ii) Impurities are more soluble in molten metal than in solid metal.
(iii) Different components of a mixture are differently adsorbed on an absorbent.
(iv) Vapours of the volatile compound can be decomposed in pure metal.
Answer:
The answer is option (ii).
The basic principle of zone refining method is that impurities are more soluble in molten metal compared to the solid state of the metal.
Question 6. In the extraction of copper from its sulphide ore, the metal is formed by the reduction of $Cu_{2}O$ with
$(i) \; FeS$
$(ii) \; CO$
$(iii) \; Cu_{2}S$
$(iv) \; SO_{2}$
Answer:
The answer is option (iii).
In the process of extraction of copper from its sulphide ore, the metal is formed by the reduction of $Cu_{2}O$ with $Cu_{2}S$
Since, copper is reduced by itself the process is known as autoreduction.
Chemical reaction occuring in this reaction is $Cu_2 O+\frac{1}{2} Cu_2 S\rightarrow 3Cu+\frac{1}{2} SO_2$
In this process, copper appears as blister copper.
Question 7. Brine is electrolysed by using inert electrodes. The reaction at anode is ________.
(i) $Cl^{-}(aq.)\rightarrow \frac{1}{2}Cl_{2}(g)+e^{-};E^{o}cell=1.36 \; V$
(ii) $2H_{2}O(l)\rightarrow O_{2}(g)+4H^{+}+4e^{-};E^{o}cell=1.23 \; V$
(iii) $Na^{+}(aq)+e^{-}\rightarrow Na (s);E^{0}cell=2.71\; V$
(iv) $H^{+}(aq)+e^{-}\rightarrow \frac{1}{2}H_{2} (g);E^{0}cell=0.00\; V$
Answer:
The answer is option (i).
Electrolysis of brine solution is a process of decomposition of $NaCl$ solution using the electric current. The anode is positive; therefore, it attracts negative hydroxide and chlorine ions. Chloride ions get oxidized by electron loss to chlorine molecules.
Question 8. In the metallurgy of aluminium ________________.
(i) $Al^{3+}$ is oxidised to $Al (s)$.
(ii) The graphite anode is oxidised to carbon monoxide and carbon dioxide.
(iii) The oxidation state of oxygen changes in the reaction at the anode.
(iv) The oxidation state of oxygen changes in the overall reaction involved in the process
Answer:
The answer is option (ii).
The graphite anode is oxidised to carbon monoxide $(CO)$ and carbon dioxide $(CO_{2})$ in the process of metallurgy of aluminium.
$C(s)+O^{2-}(melt)\rightarrow CO(g)+2e^{-}$
$C(s)+2O^{2-}(melt)\rightarrow CO_{2}(g)+4e^{-}$
Question 9. Electrolytic refining is used to purify which of the following metals?
$(i) \; Cu \; and\; Zn$
$(ii) \; Ge \; and \; Si$
$(iii)\; Zr \; and\; Ti$
$(iv) \; Zn \; and\; Hg$
Answer:
The answer is option (i).
Copper and zinc can be purified by using the electrolyte refining method. In this process, impure metal acts as anode and a strip of pure metal is used as a cathode. Impurities from the blister copper or impure zinc deposit are used as anode mud. The electrolytic refining of copper and zinc is done to get high-grade metals.
Question 10 Extraction of gold and silver involves leaching the metal with $CN^-$ ion. The metal is recovered by ________________.
(i) displacement of metal by some other metal from the complex ion.
(ii) Roasting of the metal complex.
(iii) Calcination followed by roasting.
(iv) thermal decomposition of the metal complex.
Answer:
The answer is option (i).
Extraction of gold and silver involves leaching with $CN-$ ion. The metal in the cyanide process is recovered by displacement of metal by some other metal from the complex ion. The reaction taking place is as:
$4M+8CN^{-}+2H_{2}O+O_{2}\rightarrow 4[M(CN)_{2}]^{-}+4OH^{-}$
$2[M(CN)_{2}]^{-}+Zn\rightarrow [Zn(CN)_{4}]^{2-}+2M$
Question 11 Answer the questions 11-13 on the basis of Fig. 6.1.
Choose the correct option of temperature at which carbon reduces $\text {FeO}$ to iron and produces $\text {CO}$.
(i) Below temperature at point A.
(ii) Approximately at the temperature corresponding to point A.
(iii) Above the temperature at point A but below the temperature at point D.
(iv) The above temperature at point A.
Answer:
The answer is option (iv).
$\text {FeO+C}\rightarrow \text {Fe+CO}$
It can be seen as a couple of two simpler reactions
$\text {FeO}\rightarrow \text {Fe+}\frac{1}{2}\text {O}_{2}(\Delta \text {G}^{0}_{FeO.Fe})$
$\text {C+}\frac{1}{2}\text {O}_{2}\rightarrow \text {CO}(\Delta \text {G}^{0}_{C.CO})$
Total Gibbs energy change becomes $\Delta \text {G}^{0}_{C.CO}+\Delta\text {G}_{FeO.Fe}^{0}$
In $\Delta \text {G}^{0}$ versus T plot, the plot $\text {Fe}$ to $\text {FeO}$ goes upward and the plot for $\text {C}$ to $\text {CO}$ goes downwards.
At temperature above point A, the $\text {C}$ to $\text {CO}$ lines comes below $\text {Fe}$ to $\text {FeO}$ and $\Delta \text {G}^{0}_{C,CO} < \Delta \text {G}^{0}_{Fe, FeO}$
So in this range, $\text {C}$ will reduce $\text {FeO}$ to $\text {Fe}$ and itself be oxidised to $\text {CO}$.
Question 12. Below point ‘A’ $\text {FeO}$ can ______________.
(i) be reduced by carbon monoxide only.
(ii) be reduced by both carbon monoxide and carbon.
(iii) be reduced by carbon only.
(iv) not be reduced by both carbon and carbon monoxide.
Answer:
The answer is option (i).
Below point A, $\text {FeO}$ can be reduced by carbon monoxide only.
Question 13. For the reduction of $\text {FeO}$ at the temperature corresponding to point D, which of the following statements is correct?
(i) $\Delta \text {G}$ value for the overall reduction reaction with carbon monoxide is zero.
(ii) $\Delta \text {G}$ value for the overall reduction reaction with a mixture of 1 mol carbon and 1 mol oxygen is positive.
(iii) $\Delta \text {G}$ value for the overall reduction reaction with a mixture of 2 mol carbon and 1 mol oxygen will be positive.
(iv) $\Delta \text {G}$ value for the overall reduction reaction with carbon monoxide is negative.
Answer:
The answer is option (i).
At point D, the curves of oxidation of iron and oxidation of $\text {CO}$ intersect each other.
Thus, $\Delta \text {G}^{0}$ for the reaction $\text {FeO+CO}\rightarrow \text {Fe+CO}_{2}$ is zero.
$\text {2FeO+O}_{2}\rightarrow \text {2FeO};\Delta \text {G}^{0}=-280$
$\text {2CO+O}_{2}\rightarrow \text {2CO};\Delta \text {G}^{0}=-280$
Resulting in $\text {2FeO+2CO}_{2}\rightarrow \text {2Fe+2CO}_{2}$
$\Delta \text {G}^{0}= (-280+280)=0$
The class 12 chemistry chapter 6 questions are provided here with simple explanations. Learn more through these advanced MCQs
Question 14. At the temperature corresponding to which of the points in Fig.6.1, $\text {FeO}$ will be reduced to $\text {Fe}$ by coupling the reaction $\text {2FeO}\rightarrow \text {2Fe+O}_{2}$ with all of the following reactions?
(i) $\text {C+O}_{2}\rightarrow \text {CO}_{2}$
(ii) $\text {2C+O}_{2}\rightarrow \text {2CO}$ and
(iii) $\text {2CO+O}_{2}\rightarrow \text {2CO} _{2}$
(i) Point A
(ii) Point B
(iii) Point D
(iv) Point E
Answer:
The answer is option (ii, iv).
The reduction reaction ranges can be determined from the intersection points on $\Delta \text {G}^{0}$ versus T plots.
The reduction of $\text {FeO}$ to $\text {Fe}$ takes place at point B and E because at these points $\Delta \text {G}^{0}$ value of all three oxidation reactions is less than that of the reduction reaction.
Question 15. Which of the following option are correct?
(i) Cast iron is obtained by remelting pig iron with scrap iron and coke using a hot air blast.
(ii) In the extraction of silver, silver is extracted as a cationic complex.
(iii) Nickel is purified by zone refining.
(iv) $\text {Zr and Ti}$ and are purified by van Arkel method
Answer:
The answer is option (i, iv).
Iron obtained from blast containing about 4% carbon and many impurities such as Mn, P, Si, etc, is called pig iron. It is remelted with scrap iron to obtain cast iron which has slightly less carbon content (3%) compared to pig iron and is extremely hard and brittle.
For refining of $\text {Zr and Ti}$ Van Arkel method, based on the thermal decomposition of metal component, is used. In this method, the impurities i.e. oxygen and nitrogen, are removed by heating the metal in an evacuated vessel with iodine.
$\text {Zr (s)}+\text {2 I}_{2}\overset{\text {280 k}}{\longrightarrow}\text {ZrI}_{4}\text {(g)} \overset{\text {2075 k}}{\longrightarrow}\text {Zr (s)}\text {(pure)}+\text {2 I}_{2}$
$\text {Ti}+\text {2I}_{2}\overset{\text {530 k}}{\longrightarrow}\text {TI}_{4}\overset{\text {1700 k}}{\rightarrow}\text {Ti}+\text {2I}_{2}$
Zone refining is used for semiconductors like Ge, Si. For the purification of Nickel, Mond’s process is used.
Question 16. In the extraction of aluminium by Hall-Heroult process, purified $\text {Al}_{2}\text {O}_{3}$ is mixed with $\text {CaF}_{2}$ to
(i) lower the melting point of $\text {Al}_{2}\text {O}_{3}$
(ii) increase the conductivity of the molten mixture.
(iii) reduce $\text {Al}^{3+}$ into Al(s).
(iv) acts as a catalyst
Answer:
The answer is option (i, ii).
Purified $\text {Al}_{2}\text {O}_{3}$ is mixed with $\text {CaF}_{2}$ in Hall-Heroult process to lower the melting point of $\text {Al}_{2}\text {O}_{3}$ and increase the conductivity of the molten mixture. Hence, options a and b are correct.
Question 17. Which of the following statements is correct about the role of substances added in the froth floatation process?
(i) Collectors enhance the non-wettability of the mineral particles.
(ii) Collectors enhance the wettability of gangue particles.
(iii) By using depressants in the process, two sulphide ores can be separated.
(iv) Froth stabilisers decrease the wettability of gangue.
Answer:
The answer is option (i, iii).
To enhance the non-wettability of mineral particles as well as froth stabilisers, collectors like sodium ethyl xanthate are used.
For example, sodium cyanide acts as a depressant for zinc sulphide in the process of concentration of galena ore. Depressants can be used for the separation of two sulphide ores.
Froth stabilisers are used to stabilise the froth in the process.
Question 18. In the Froth Floatation process, zinc sulphide and lead sulphide can be separated by ______________.
(i) using collectors.
(ii) adjusting the proportion of oil to water.
(iii) using a depressant.
(iv) using froth stabilisers.
Answer:
The answer is option (ii, iii).
The froth flotation method is used in the extraction of metal from sulphide ore. The two sulphide ores can be separated by using a depressant and adjusting the proportion of oil to water in the froth flotation process. Depressant used in the separation of zinc sulphide and lead sulphide is $NaCN$. It is utilised in the selective prevention of $ZnS$ from coming to the froth.
Question 19. Common impurities present in bauxite are ____________.
(i) $\text {CuO}$
(ii) $\text {ZnO}$
(iii) $\text {Fe}_{2}\text {O}_{3}$
(iv) $\text {SiO}_{2}$
Answer:
The answer is option (iii, iv).
Bauxite is an ore of aluminium which contain $\text {Fe}_{2}\text {O}_{3}$ and $\text {SiO}_{2}$ as common impurities. Also some of the major impurities in bauxite are iron oxides (goethite and hematite), silicon dioxide, kaolinite and small amounts of anatase.
Question 20. Which of the following ores are concentrated by froth flotation?
(i) Haematite
(ii) Galena
(iii) Copper pyrites
(iv) Magnetite
Answer:
The answer is option (ii, iii).
Sulphide ores are concentrated by the froth flotation process as pine oil selectively wets the sulphide ore. Galena and copper pyrite, being sulphide ores are concentrated by the froth flotation process.
Question 21. Which of the following reactions occur during calcination?
(i) $\text {CaCO}_{3}\rightarrow \text {CaO}+ \text {CO}_{2}$
(ii) $\text {2FeS}_{2}+\frac{11}{2}\text {O}_{2}\rightarrow \text {Fe}_{2}\text {O}_{3}+ \text {4SO}_{2}$
(iii) $\text {Al}_{2}\text {O}_{3}.x\text {H}_{2}\text {O}\rightarrow \text {Al}_{2}\text {O}_{3}+ x \text {H}_{2}\text {O}$
(iv) $\text {ZnS}+\frac{3}{\text {2}}O_{2}\rightarrow \text {ZnO}+\text {SO}_{2}$
Answer:
The answer is option (i, iii).
In the process of calcination, heating of the ore below its melting in a limited supply of air takes place. Ores that contain oxygen like oxide, hydroxides or carbonates are calcined. The reaction that takes place is:
$\text {CaCO}_{3}\overset{\Delta }{\rightarrow}\text {CaO}+\text {CO}_{2}$
$\text {Al}_{2}\text {O}_{3}.\text {xH}_{2}\text {O}\overset{\Delta }{\rightarrow}\text {Al}_{2}\text {O}_{3}+ \text {xH}_{2}\text {O}$
Question 22. For the metallurgical process of which of the ores calcined ore can be reduced by carbon?
(i) haematite
(ii) calamine
(iii) iron pyrites
(iv) sphalerite
Answer:
The answer is option (i, ii).
Oxide reduction can be done by using carbon. Haematite (Iron ore - $\text {Fe}_{2}\text {O}_{3}$ ) and calamine $\text {ZnCO}_{3}\rightarrow \text {ZnO}+\text {CO}_{2}$ contain oxygen, so they can be reduced by carbon.
Sulphide ores cannot be reduced by carbon. Iron pyrite and sphalerite are sulphide ores of iron and zinc, respectively.
Question 23. The main reactions occurring in the blast furnace during the extraction of iron from haematite are ________.
(i) $\text {Fe}_{2}\text {O}_{3}+\text {3CO}\rightarrow \text {2Fe}+\text {3CO}_{2}$
(ii) $\text {FeO}+\text {SiO}_{2}\rightarrow \text {FeSiO}_{3}$
(iii) $\text {Fe}_{2}\text {O}_{3}+\text {3C}\rightarrow \text {2Fe}+\text {3CO}$
(iv) $\text {CaO}+\text {SiO}_{2}\rightarrow \text {CaSiO}_{3}$
Answer:
The answer is the option (i, iv).
The 2 main reactions taking place in the blast furnace during the extraction of iron are:
(i) Reduction of $\text {Fe}_{2}\text {O}_{3}+\text {CO}\rightarrow \text {2FeO}+\text {CO}_{2}$
$\text {2FeO}+\text {2CO}\rightarrow \text {2Fe}+\text {2CO}_{2}$
$\text {Fe}_{2}\text {O}_{3}+\text {3CO}\rightarrow \text {2Fe}+\text {3CO}_{2}$
(ii) Slag formation $\text {CaO}+\text {SiO}_{2}\rightarrow \text {CaSiO}_{3} \; \text {Fusible slag}$
Question 24. In which of the following method of purification, metal is converted to its volatile compound which is decomposed to give pure metal?
(i) heating with a stream of carbon monoxide.
(ii) heating with iodine.
(iii) liquation.
(iv) distillation.
Answer:
The answer is option (i,ii)
(i) Heating of Nickel with Carbon Monoxide (Mond's Process):
$
\mathrm{Ni}+4 \mathrm{CO} \rightarrow \mathrm{Ni}(\mathrm{CO})_4 \xrightarrow{450-470 \mathrm{~K}} \mathrm{Ni}+4 \mathrm{CO}
$
(ii) Heating with lodine (Van Arkel Method for Zirconium):
$
\mathrm{Zr}+2 \mathrm{I}_2 \xrightarrow{870 \mathrm{~K}} \mathrm{ZrI}_4 \xrightarrow[\text { (Tungsten filament) }]{2075 \mathrm{~K}} \mathrm{Zr}+2 \mathrm{I}_2
$
Question 25. Which of the following statements are correct?
(i) A depressant prevents a certain type of particle from coming to the froth.
(ii) Copper matte contains $\text {Cu}_{2}\text {S}$ and $\text {ZnS}$
(iii) The solidified copper obtained from the reverberatory furnace has a blistered appearance due to the evolution of $\text {SO}_{2}$ during the extraction.
(iv) Zinc can be extracted by self-reduction.
Answer:
The answer is option (i, iii).
Frothing of a particular sulphide can be prevented by depressants. The solidified copper that we get in the reverberatory furnace has a blistered appearance due to evolution of $\text {SO}_{2}$ during extraction. Hence, it is called blister copper.
Question 26. In the extraction of chlorine from brine _____________.
(i) $\Delta \text {G}^{0}$ for the overall reaction is negative.
(ii) $\Delta \text {G}^{0}$ for the overall reaction is positive.
(iii) $\text {E}^{0}$ for the overall reaction has negative value.
(iv) $\text {E}^{0}$ for the overall reaction has positive value.
Answer:
The answer is option (ii,iii).
$3Cl^{-}+2H_{2}O\rightarrow 2OH^{-}+H_{2}+Cl_{2}$
$\Delta G^{0}$ for the reaction is $+422\; kJ$
Using $\Delta G^{0}=-nFE^{0},$ we get
$E^{0}=-2.2\; V$
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Here some short answer type questions from NCERT Exemplar Solutions for Class 12 Chemistry Chapter 6 are given for practice. This section contains important questions that are asked in the exams.Practice short answer types from the questions below
Question 27. Why is an external emf of more than 2.2V required for the extraction of $Cl_{2}$ from brine?
Answer:
In the process of extraction of $\mathrm{Cl}_2$ from brine solution:
$2 \mathrm{Cl}^{-}(\mathrm{aq})+2 \mathrm{H}_2 \mathrm{O}(\mathrm{l}) \rightarrow 2 \mathrm{OH}^{-}(\mathrm{aq})+\mathrm{H}_2(\mathrm{~g})+\mathrm{Cl}_2(\mathrm{~g})$ the value of $\Delta \mathrm{G}^{\ominus}$ is $(+ 422 \mathrm{KJ})$.
For this the value of $E^{\Theta}$ is $\Delta G^{\Theta}=-n F E^{\Theta}$ or
$E^{\Theta}=-\frac{\Delta G^{\Theta}}{n F}$
$=-\frac{422 \times 10^3 \mathrm{~J}}{2 \times 96500}$
$=-2.20 \mathrm{~V}$
Hence, an external emf more than 2.20 V is required for the extraction of $Cl_{2}$ from brine solution for the electrolysis process.
Answer:
As per the Ellingham diagram at temperatures greater than 1073 K, $\Delta G^{0}$ for the formation $FeO$ is less negative than $\Delta G^{0}$ for the formation of carbon monoxide from carbon.
Thus, above 1073 K, carbon can reduce $FeO$, i.e., $\Delta_{r} G^{0}$ for the reaction
$\mathrm{FeO}+\mathrm{C} \xrightarrow{>1073 \mathrm{~K}} \mathrm{Fe}+\mathrm{CO} \quad \Delta G<0$
Answer:
Wrought iron is an alloy with a very low carbon content (less than 0.08%).
The reaction is:
$Fe_{2}O_{3}+3C\rightarrow 2Fe+3CO$
In the extraction of cast iron from haematite ore, on the addition of limestone as flux, the impurities of sulphur, silicon and phosphorus pass into slag on changing to their oxides.
Question 30. How is copper extracted from low-grade copper ores?
Answer:
Copper is extracted from low-grade ores by the process of hydrometallurgy. Acid or bacteria is used in its leaching process. In the process, ore is treated with a suitable regent that dissolves ore but not the impurities. Scrap iron, zinc or $H_{2}$ is used to treat the solution containing copper ions $(Cu^{+2})$ and the reactions are as:
$Cu^{2+} (aq)+H_{2} (g) \rightarrow Cu(s)+2H^{+} (aq)$
$Cu^{2+} (aq)+Fe (s) \rightarrow Cu(s)+Fe^{2+} (aq)$
In this way, copper is obtained.
Question 31. Write two basic requirements for refining of metal by Mond process and by Van Arkel Method
Answer:
Mond’s process and Van Arkel method are used for refining of nickel and zinc, respectively. The basic requirements for both processes are:
(i) A volatile compound should be formed by the metal on reaction with an available reagent.
(ii) The volatile compound formed should be easily decomposable, enabling the metal to be easily recovered.
Answer:
Despite being better reducing agents, carbon and hydrogen are not used as carbon and hydrogen form carbides and hydrides, respectively, on reaction with metals at high temperature.
Question 33. How do we separate two sulphide ores by Froth Floatation Method? Explain with an example.
Answer:
The separation of two sulphide ores is done by adjusting the proportion of oil to water or by using depressants. $NaCN$ is used for an ore containing $ZnS$ and $PbS$. Sodium cyanide forms complex with $ZnS$ and prevents it from coming with froth but lead sulphide remains with froth.
$4NaCN+ZnS\rightarrow Na_{2}Zn(CN)_{4}+Na_{2}S$
Answer:
Haematite $(Fe_{2}O_{3})$ is used to line the furnace. It supplies the oxygen and oxidises impurities present in the cast iron like carbon, silicon, manganese and phosphorus to $CO, SiO_{2}, MnO$ and $P_{2}O_{5}$.
$Fe_{2}O_{3}+3C\overset{Heat}{\longrightarrow}2Fe+3CO$
$3Si+2Fe_{2} O_3\rightarrow 4Fe+3SiO_2$
$3S+2Fe_2 O_3\rightarrow 3SO_2+4Fe$
$CO$ and $SO_{2}$ escape and $MnO \; and\; SiO_{2}$ combine to form to form manganous silicate $(MnSiO_{3})$ as slag $MnO+SiO_{2}\overset{Heat}{\longrightarrow}MnSiO_{3}$ (Manganous silicate-slag)
Answer:
Compound B is more readily adsorbed on the column as compound A is eluted in preference to compound B
Question 36. Why is sulphide ore of copper heated in a furnace after mixing with silica?
Answer:
Iron oxide that is present as an impurity in the sulphide ore of copper forms an iron silicate slag and copper is produced in the form of copper matte. This is why the sulphide ore of copper is heated in a furnace after mixing with silica.
$FeO+SiO_{2}\rightarrow FeSiO_{3}$
Question 37. Why are sulphide ores converted to oxide before reduction?
Answer:
Sulphides are not reduced easily, unlike the oxides. This is why sulphides are first oxidised and then subjected to reduction.
Question 38. Which method is used for refining $Zr \; and\; Ti$ ? Explain with equation.
Answer:
Van Arkel method is used in refining of $Zr \; and\; Ti$. The crude metal, on heating with iodine, forms a volatile, unstable compound. Pure metal is then obtained by decomposing the compound.
The equations are :
$\text {Zr (s) (impure)+2I}_{2}\overset{870\; K}{\longrightarrow}\text {ZrI}_{4}$
$\text {ZrI}_{4}\overset{1800\; K}{\longrightarrow}\text {Zr (pure)+2I}_{2}$
$\text {Ti (impure)+2I}_{2}\overset{523\; K}{\longrightarrow}\text {TiI}_{4} \text {(g)}$
$\text {TiI}_{4}\overset{1700\; K}{\longrightarrow}\text {Ti (pure)+2I}_{2}$
Question 39. What should be the considerations during the extraction of metals by electrochemical method?
Answer:
During the extraction of metals by the electrochemical method, we should keep in mind the following factors
(i) Reactivity of the metal.
(ii) Suitability of the electrode.
Question 40. What is the role of flux in metallurgical processes?
Answer:
Flux is a chemical cleaning agent.
The ores contain some gangue even after concentration. Certain substances are mixed with concentrated ore for the purpose of removing the gangue. They combine with the gangue to form a fusible material that is insoluble in molten metal. These substances are called fluxes. Some examples of materials used as flux: Limestone, silica, dolomite, lime, borax etc.
Fluxes are classified as acidic or basic based on the type of impurities they remove.
$SiO_{2}\; (Acidic\; acid)+CaO\; (basic\; impurity)\rightarrow CaSiO_{3}(Slag)$
$MgO\; (basic\; flux)+SiO_{2}\; (Acidic\; impurity)\rightarrow MgSiO_{3}(Slag)$
Question 41. How are metals used as semiconductors refined? What is the principle of the method used?
Answer:
Semiconductor like silicon and germanium is produced by zone refining method and the principle used is that the impurities are more soluble in melt than the corresponding solid state of metals.
Answer:
The reactions that take place in blast furnace during the metallurgy of iron at the temperature range 500-800 K are:
$3Fe_{2}O_{3}+CO\rightarrow 2Fe_{3}O_{4}+CO_{2}$
$Fe_{3}O_{4}+4CO\rightarrow 3Fe+4CO_{2}$
$Fe_{2}O_{3}+CO\rightarrow 2FeO+CO_{2}$
Question 43. Give two requirements for vapour phase refining.
Answer:
The two requirements for vapour phase refining are:
(i) A volatile compound should be formed by the metal on reaction with an available reagent.
(ii) The volatile compound formed should be easily decomposable, enabling the metal to be easily recovered.
Answer:
In the extraction of gold by the cyanide process, gold particles present in the ore are treated with a dilute solution of $NaCN$ in the presence of atmospheric oxygen. Gold particles dissolve by forming a complex cyanide that is soluble in nature.
$4Au+8NaCN+2H_{2}O+O_{2}\rightarrow 4Na[Au(CN)_{2}]+4NaOH$
On adding an electropositive metal like zinc, Au is recovered from solution.
$2Na [Au(CN)_{2}]+Zn\rightarrow Na_{2}[Zn(CN)_{4}]+2Au$
The process of extraction of gold by cyanide oxidation as well as reduction. Oxidation of gold takes place during the formation of the cyanide complex, whereas reduction takes place during its recovery. $Zn$ acts as a reducing agent.
Chemistry chapter 6 important questions are discussed below. These are generally asked in exams to test your knowledge. These solutions are quite helpful for competitive exams.
Question 45. Match the items of Column I with items of Column II and assign the correct code:
|
Column I |
Column II |
|
(A) Pendulum |
(1) Chrome steel |
|
(B) Malachite |
(2) Nickel steel |
|
(C) Calamine |
(3) $Na_{3}AlF_{6}$ |
|
(D) Cryolite |
(4) $CuCO_{3}.Cu(OH)_{2}$ |
|
|
(5) $ZnCO_{3}$ |
(i) A (1) B (2) C (3) D (4)
(ii) A (2) B (4) C (5) D (3)
(iii) A (2) B (3) C (4) D (5)
(iv) A (4) B (5) C (3) D (2)
Answer:
Option (ii) is the answer.
Pendulum clocks use nickel steel due to its low thermal expansion. Malachite is a basic copper carbonate ore with the formula $\mathrm{CuCO}_3 \cdot \mathrm{Cu}(\mathrm{OH})_2$. Calamine is zinc carbonate, represented as $\mathrm{ZnCO}_3$. Cryolite, $\mathrm{Na}_3 \mathrm{AlF}_6$, is used as a flux in the extraction of aluminium.
Question 46. Match the items of Column I with the items of Column II and assign the correct code :
|
Column I |
Column II |
|
(A) Coloured bands |
(1) Zone refining |
|
(B) Impure metal to volatile complex |
(2) Fractional distillation |
|
(C) Purification of $Ge \; and \; Si$ |
(3) Mond Process |
|
(D) Purification of mercury |
(4) Chromatography |
|
|
(5) Liquation |
(i) A (1) B (2) C (4) D (5)
(ii) A (4) B (3) C (1) D (2)
(iii) A (3) B (4) C (2) D (1)
(iv) A (5) B (4) C (3) D (2)
Answer:
Option (ii) is the answer.
Chromatography shows coloured bands as it separates components based on their movement through a medium. The Mond process involves forming a volatile complex to purify nickel. Zone refining is used to purify semiconductors like germanium and silicon. Mercury is purified by fractional distillation due to its volatility.
Question 47. Match items of Column I with the items of Column II and assign the correct code :
|
Column I |
Column II |
|
(A) Cyanide process |
(1) Ultrapure Ge |
|
(B) Froth Flotation Process |
(2) Dressing of $ZnS$ |
|
(C) Electrolytic reduction |
(3) Extraction of $Al$ |
|
(D) Zone refining |
(4) Extraction of $Au$ |
|
|
(5) Purification of $Ni$ |
(i) A (4) B (2) C (3) D (1)
(ii) A (2) B (3) C (1) D (5)
(iii) A (1) B (2) C (3) D (4)
(iv) A (3) B (4) C (5) D (1)
Answer:
Option (i) is the answer.
The cyanide process is used for the extraction of gold (Au) by forming soluble complexes. The froth flotation process is used for the concentration (dressing) of zinc sulfide (ZnS) ores. Electrolytic reduction is used in the extraction of reactive metals like aluminium (Al).
Zone refining is used to obtain ultrapure semiconductors like germanium (Ge).
Question 48. Match the items of Column I with the items of Column II and assign the correct code:
|
Column I |
Column II |
|
(A) Sapphire |
(1) $\text {Al}_{2}\text {O}_{3}$ |
|
(B) Sphalerite |
(2) $\text {NaCN}$ |
|
(C) Depressant |
(3) $\text {Co}$ |
|
(D) Corundum |
(4) $\text {ZnS}$ |
|
|
(5) $\text {Fe}_{2}\text {O}_{3}$ |
(i) A (3) B (4) C (2) D (1)
(ii) A (5) B (4) C (3) D (2)
(iii) A (2) B (3) C (4) D (5)
(iv) A (1) B (2) C (3) D (4)
Answer:
Option (i) is the answer.
Sapphire and corundum are both crystalline forms of aluminium oxide (Al₂O₃). Sphalerite is the mineral name for zinc sulfide (ZnS). In metallurgy, sodium cyanide (NaCN) acts as a depressant by preventing the flotation of certain minerals like zinc sulfide during the extraction of metals like lead.
Question 49. Match the items of Column I with items of Column II and assign the correct code :
|
Column I |
Column II |
|
(A) Blistered $Cu$ |
(1) Aluminium |
|
(B) Blast furnace |
(2) $2Cu_{2}O+Cu_{2}S\rightarrow 6Cu+SO_{2}$ |
|
(C) Reverberatory furnace |
(3) Iron |
|
(D) Hall-Heroult process |
(4) $FeO+SiO_{2}\rightarrow FeSiO_{3}$ |
|
|
(5) $2Cu_{2}S+3O_{2}\rightarrow 2Cu_{2}O+2SO_{2}$ |
(i) A (2) B (3) C (4) D (1)
(ii) A (1) B (2) C (3) D (5)
(iii) A (5) B (4) C (3) D (2)
(iv) A (4) B (5) C (3) D (2)
Answer:
Option (i) is the answer.
Blistered copper forms during the self-reduction of copper ores: $2 C u_2 O+C u_2 S \rightarrow$ $6 C u+S O_2$.
The blast furnace is used for iron extraction, where slag is formed: $\mathrm{FeO}+\mathrm{SiO}_2 \rightarrow$ $\mathrm{FeSiO}_3$.
The reverberatory furnace oxidizes copper(I) sulfide to copper(I) oxide: $2 C u_2 S+$ $3 \mathrm{O}_2 \rightarrow 2 \mathrm{Cu}_2 \mathrm{O}+2 \mathrm{SO}_2$.
The Hall-Héroult process is used to extract aluminium from alumina.
This is one of the most important sections covered in the NCERT exemplar solutions Class 12 chemistry chapter 6. These questions will improve your critical thinking.The most typical and important section for exams
Question 50. In the following question, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: Nickel can be purified by Mond process.
Reason:$Ni(CO)_{4}$ is a volatile compound which decomposes at 460K to give pure $Ni$.
(i) Both assertion and reason are true and the reason is the correct explanation of assertion.
(ii) Both assertion and reason are true but the reason is not the correct explanation of assertion.
(iii) The assertion is true but the reason is false.
(iv) The assertion is false but the reason is true.
(v) Assertion and reason both are wrong.
Answer:
The answer is option (i).
For Mond’s process, the prerequisites include:
(i) A volatile compound should be formed by the metal on reaction with an available reagent.
(ii) The volatile compound formed should be easily decomposable, enabling the metal to be easily recovered.
$Ni(CO)_{4}$ is a volatile compound which decomposes to give pure nickel on heating at 460 K while $CO$ (Carbon monoxide) is removed as gas.
Question 51 In the following question, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: Zirconium can be purified by Van Arkel method.
Reason: $ZrI_{4}$ is volatile and decomposes at 1800K.
(i) Both assertion and reason are true and the reason is the correct explanation of assertion.
(ii) Both assertion and reason are true but the reason is not the correct explanation of assertion.
(iii) The assertion is true but the reason is false.
(iv) The assertion is false but the reason is true.
(v) Assertion and reason both are wrong.
Answer:
The answer is option (i).
Zirconium is also purified by Van Arkel method as it forms $ZrI_{4}$ on treating with iodine and is easily decomposed to get pure zirconium.
Question 52. In the following question, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: Sulphide ores are concentrated by Froth Flotation method.
Reason: Cresols stabilise the froth in the Froth Flotation Method.
(i) Both assertion and reason are true and the reason is the correct explanation of assertion.
(ii) Both assertion and reason are true but the reason is not the correct explanation of assertion.
(iii) The assertion is true but the reason is false.
(iv) The assertion is false but the reason is true.
(v) Assertion and reason both are wrong.
Answer:
The answer is option (ii).
Sulphide ores, on being wetted by oil, become lighter and rises to the surface along with froths. On the other hand, impurities wetted by water settle down as they get heavier.
Question 53. In the following question, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: Zone refining method is very useful for producing semiconductors.
Reason: Semiconductors are of high purity.
(i) Both assertion and reason are true and the reason is the correct explanation of assertion.
(ii) Both assertion and reason are true but the reason is not the correct explanation of assertion.
(iii) The assertion is true but the reason is false.
(iv) The assertion is false but the reason is true.
(v) Assertion and reason both are wrong.
Answer:
The answer is option (ii).
The principle of the zone refining method is that the the impurities of semiconductors are more soluble in the molten zone compared to the solid state and the ultrapure semiconductor crystallizes.
Question 54 In the following question, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: Hydrometallurgy involves dissolving the ore in a suitable reagent followed by precipitation by a more electropositive metal.
Reason: Copper is extracted by hydrometallurgy.
(i) Both assertion and reason are true and the reason is the correct explanation of the assertion.
(ii) Both assertion and reason are true but the reason is not the correct explanation of assertion.
(iii) The assertion is true but the reason is false.
(iv) The assertion is false but the reason is true.
(v) Assertion and reason both are wrong.
Answer:
The answer is option (ii).
Copper is extracted by a hydrometallurgical process. Suitable solvent like water is used for dissolving salts of metal. They are then reduced by more electropositive element in this process.
The following are the long-answer type questions that needs more practice. These are the chemistry chapter 6 important questions that are asked in the exams.
Answer:
(i) As per the Ellingham diagram, below 710 K
$\Delta G_{C,CO_{2}}^{0}<\Delta G_{C,CO}^{0}$
Hence, $CO_{2}$ is better reducing agent compared to $CO$.
At temperature above 710 K, $\Delta G_{C,CO_{2}}^{0}<\Delta G_{C,CO}^{0}$
Hence, $CO$ is better reducing agent.
(ii) Sulphide ores cannot be reduced easily but oxide ores can be esily reduced compared to them, hence sulphide ores are generally converted into oxides before reduction
(iii) In addition to copper sulphide, copper pyrites contain iron sulphide. In reverberatory furnace copper ore is roasted to give oxides.
$FeO$ is removed by adding silica from the matte containing copper sulphide and some iron sulphide.
$2FeS+3O_{2}\rightarrow 2FeO+2SO_{2}$
$FeO+SiO_{2}\rightarrow FeSiO_{3}$
(iv) Carbon and hydrogen react with metals at high temperature to form carbides and hydrides respectively hence they are not used as reducing agents.
(v) $Ti$ reacts with iodine to form $TiI_{4}$ which is volatile and decomposes to give $Ti$ at high temperature to give extra pure titanium. That is why vapour phase refining method is used for purification of $Ti$
$Ti + 2I_{2}\overset{530 K}{\rightarrow}TiI_{4}\overset{1800 K}{\rightarrow}Ti+2I_{2}$
Some Class 12 chemistry chapter 6 questions and answers are given below that will help you tackle complex problems. The questions below will help you evaluate your understanding of the concepts.
Question 1: Which among the following is used to reduce$\mathrm{TiCl}_4$ to Ti?
(1) C
(2) Al
(3) Mg
(4) H2
Answer: Titanium dioxide is reacted with chlorine to form titanium tetrachloride, which is then reacted with magnesium to remove the chlorine and leave behind the pure metal.
In Kroll's process for titanium, Mg is used as a reducing agent
$
\mathrm{TiCl}_4+2 \mathrm{Mg} \rightarrow 2 \mathrm{MgCl}_2+\mathrm{Ti}
$
This represents the reduction of titanium tetrachloride $\left(\mathrm{TiCl}_4\right)$ with magnesium to produce titanium metal and magnesium chloride.
Hence, the correct answer is option (3).
Question 2: Roasting of sulphides gives the gas ‘A’ as a by- product. ‘A’ is a colourless gas with choking smell of burnt sulphur and causes great damage to respiratory organs as a result of acid rain. Its aqueous solution is acidic acts as a reducing agent and its acid is known only in solution. The gas ‘A’ is
(1) $\mathrm{SO}_2$
(2) $\mathrm{CO}_2$
(3) $\mathrm{SO}_3$
(4) $\mathrm{H}_2 \mathrm{~S}$
Answer:
Gas ' $A$ ' is Sulphur dioxide $\mathrm{SO}_2 . \mathrm{SO}_2$ is a colourless gas which can cause damage to respiratory organs. Its aqueous solution is acidic
$
\mathrm{SO}_2+\mathrm{H}_2 \mathrm{O} \rightarrow \mathrm{H}_2 \mathrm{SO}_3
$
$\mathrm{H}_2 \mathrm{SO}_3$ is sulphurous acid.
Hence, the correct answer is option (1).
Question 3: The following reaction occurs in the Blast furnace, where iron ore is reduced to iron metal
$\mathrm{Fe}_2 \mathrm{O}_{3(\mathrm{~s})}+3 \mathrm{CO}_{(\mathrm{g})} \rightleftharpoons \mathrm{Fe}_{(\mathrm{l})}+3 \mathrm{CO}_{2(\mathrm{~g})}$
Using the Le-chatelier's principle, predict which one of the following will not disturb the equilibrium.
(1) Addition of $\mathrm{Fe}_2 \mathrm{O}_3$
(2) Addition of $\mathrm{CO}_2$
(3) Removal of CO
(4) Removal of $\mathrm{CO}_2$
Answer:
When solid is added there is no effect on equilibrium. So, the addition of $\mathrm{Fe}_2 \mathrm{O}_3$ will does not disturb the equilibroum.
Hence, the answer is option (1).
Question 4: Identify the incorrect pair from the following :
(1) Carnallite $-\mathrm{KCl} \cdot \mathrm{MgCl}_2, 6 \mathrm{H}_2 \mathrm{O}$
(2) Cryolite $-\mathrm{Na}_3 \mathrm{AlF}_6$
(3) Fluroapatite - $3 \mathrm{Ca}_3\left(\mathrm{PO}_4\right)_2 \cdot \mathrm{CaF}_2$
(4) Fluorspar - $\mathrm{BF}_3$
Answer:
Fluorspar, also known as fluorite, is a mineral composed of calcium fluoride (CaF₂).
Hence, the answer is the option (4).
Question 5: Which among the following forms a slag from P2O5 impurity during the extraction of iron?
(1) $\mathrm{CaSiO}_3$
(2) $\mathrm{Ca}_3\left(\mathrm{PO}_4\right)_2$
(3) $\mathrm{Fe}_3\left(\mathrm{PO}_4\right)_2$
(4) $\mathrm{FeSiO}_3$
Answer:
During the extraction of iron, slag formed from $\mathrm{P}_2 \mathrm{O}_5$ impurities is $\mathrm{Ca}_3\left(\mathrm{PO}_4\right)_2$
$\mathrm{P}_2 \mathrm{O}_5+3 \mathrm{CaO} \rightarrow \mathrm{Ca}_3\left(\mathrm{PO}_4\right)_2$
Hence, the answer is the option (1).
To effectively solve questions from this chapter you can follow the points below to build a good strategy.
1. Identify the kind of question, such as
Conceptual- These are based on definitions or theory.
Reaction-based - These involve chemical equations.
Process-based- These are related to steps in metallurgy (e.g., roasting, smelting).
Application-based- It comes from real-life uses or comparisons.
The NCERT Exemplar Class 12 Chemistry Solutions Chapter 6 will help you understand these concepts better.
2. Revising the concepts is basic to attempt questions. Some of the important concepts are
Occurrence of metals- Ores and minerals.
Concentration of ores- Gravity separation, froth flotation, magnetic separation.
Extraction methods-
Refining methods like distillation, liquation, electrolytic refining, zone refining. Also,thermodynamic principles like Ellingham diagrams are important for examination purpose.
3. Refer to the NCERT in-text questions and exercises. You can also follow previous year questions as to get a clear idea of the exam pattern. You can get these type of questions in the NCERT Class 12 solutions available on our website.
4. Follow NCERT solved examples to know the correct way to solve the questions. The answer should contain the key points of the related concepts. Follow the NCERT solutions for detailed explanations.
The following are the important topics of chapter 6. Practice more at NCERT Class 12 chemistry chapter 6 exemplar solutions.
The following are the important formulas covered in the Class 12 NCERT Chemistry chapter 6.
1. Ellingham Equation (Qualitative form)
$
\Delta G=\Delta H-T \Delta S
$
2. Extraction of Iron (from Hematite)
$
\mathrm{Fe}_2 \mathrm{O}_3+3 \mathrm{CO} \rightarrow 2 \mathrm{Fe}+3 \mathrm{CO}_2
$
3. Extraction of Copper (from $\mathrm{Cu}_2 \mathrm{~S}$ )
$
\begin{aligned}
2 \mathrm{Cu}_2 \mathrm{~S}+3 \mathrm{O}_2 & \rightarrow 2 \mathrm{Cu}_2 \mathrm{O}+2 \mathrm{SO}_2 \\
\mathrm{Cu}_2 \mathrm{~S}+\mathrm{Cu}_2 \mathrm{O} & \rightarrow 6 \mathrm{Cu}+\mathrm{SO}_2
\end{aligned}
$
4. Purification by Mond's Process (Nickel)
$
\begin{array}{ll}
\mathrm{Ni}+4 \mathrm{CO} \rightarrow \mathrm{Ni}(\mathrm{CO})_4 & (\text { at } 330 K) \\
\mathrm{Ni}(\mathrm{CO})_4 \rightarrow \mathrm{Ni}+4 \mathrm{CO} & (\text { at } 450 K)
\end{array}
$
5. Extraction of Zinc (from ZnO)
$
\mathrm{ZnO}+\mathrm{C} \rightarrow \mathrm{Zn}+\mathrm{CO}
$
NCERT Exemplar Solutions for Class 12 Chemistry Chapter 6 help students to understand the concepts of metallurgical processes. Given below some points on advantages of using these soltions:
These NCERT Exemplar Solutions for Class 12 Chemistry are designed to help students strengthen their conceptual understanding and problem-solving skills. Here is a list of NCERT chapter-wise solutions:
NCERT Solutions for Class 12 Chemistry are prepared to help students understand complex concepts with ease. Here is a list of NCERT chapter-wise solutions:
The NCERT subject-wise solutions will help you broaden your concepts and will also help in revision. Learn more from Class 12 NCERT notes.
Excel your preparation with NCERT exemplar solutions. Click on the link below
You can follow the links given in the table below to get access to the Class 12 NCERT notes.
You can find links to the Class 12 NCERT chemistry book and syllabus for the respective subjects.
Frequently Asked Questions (FAQs)
Ores are naturally occurring rocks or minerals from which a valuable metal can be extracted economically. They contain a significant percentage of the desired metal, usually in the form of its compounds like oxides, sulfides, carbonates, halides, etc. Ores are the raw materials for the isolation of metals.
Slag is a fusible byproduct formed when the flux reacts with the gangue during the smelting of an ore. It is typically a molten salt or oxide that has a lower melting point than the metal being extracted and is immiscible with the molten metal, allowing for easy separation.
Froth flotation is based on the principle that sulfide ore particles are preferentially wetted by oil and attach to air bubbles that make them float to the surface as a froth, while the gangue particles are wetted by water and sink to the bottom. Collectors (like pine oil) stabilize the froth and depressors are used to prevent certain unwanted minerals from floating.
Liquation is a refining method used for metals that have a low melting point and are immiscible with the impurities (e.g., lead, tin). The crude metal is heated on a sloping surface. The metal fuses and flows down, leaving behind the solid, non-fusible impurities on the surface.
Roasting is the process of heating a concentrated ore strongly in the presence of excess air, usually below its melting point. This process is primarily used for
NCERT Exemplar for Chapter 6 provides advanced practice questions and detailed solutions based on the principles and processes used in the isolation and extraction of metals, helping students build deeper conceptual understanding.
Yes, this chapter is considered easy if your basics of metallurgy are clear, as most concepts are straightforward and rely on simple principles like oxidation, reduction, and refining.
Metallurgy refers to the process of extracting metals from their ores and refining them to obtain pure metal, using various physical and chemical methods.
You can download them from trusted educational sites like Careers360 and other educational platforms.
NCERT Exemplar is important because it provides higher-level, application-based questions that strengthen conceptual understanding and help students score better in both board and competitive exams.
On Question asked by student community
Hello Gilla
You can download the question paper from the link given below:
https://school.careers360.com/boards/cbse/cbse-previous-year-question-papers-class-10-maths
Hope it helps.
Hello Student,
Check the article given below to access and download the CBSE question paper for classes 10 and 12.
Link:
https://school.careers360.com/boards/cbse/cbse-previous-year-question-papers
Dear Student,
You can appear for improvement exams in other passed subjects after clearning compartment exams. The Central Board of Secondary Education (CBSE) conducts the CBSE Class 12 improvement exams for students who are not satisfied with their scores in the Class 10 and Class 12 board examinations.
You can
Hi Madhuri,
For CBSE Class 12 Maths preparation, especially if your basics are weak, please refer to the link given below:
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Hi Jatin!
Given below is the link to access CBSE Class 12 English Previous Year Questions:
https://school.careers360.com/download/ebooks/cbse-class-12-english-previous-year-question-papers
For subjectwise previous year question papers, you might find this link useful:
https://school.careers360.com/boards/cbse/cbse-previous-year-question-papers-class-12
A block of mass 0.50 kg is moving with a speed of 2.00 ms-1 on a smooth surface. It strikes another mass of 1.00 kg and then they move together as a single body. The energy loss during the collision is
| Option 1)
|
Option 2)
|
| Option 3)
|
Option 4)
|
An athlete in the olympic games covers a distance of 100 m in 10 s. His kinetic energy can be estimated to be in the range
| Option 1)
|
Option 2)
|
| Option 3)
|
Option 4)
|
A particle is projected at 600 to the horizontal with a kinetic energy . The kinetic energy at the highest point
| Option 1)
|
Option 2)
|
| Option 3)
|
Option 4)
|
In the reaction,
| Option 1)
|
Option 2)
|
| Option 3)
|
Option 4)
|
How many moles of magnesium phosphate, will contain 0.25 mole of oxygen atoms?
| Option 1)
0.02 |
Option 2)
3.125 × 10-2 |
| Option 3)
1.25 × 10-2 |
Option 4)
2.5 × 10-2 |
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