(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....
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....
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....
Assertion: Zirconium can be purified by Van Arkel method. Reason: ZrI4 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....
Assertion: Nickel can be purified by the 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....
Match the items of Column I with items of Column II.
Column I Column II (A) Pendulum (1) Chrome steel (B) Malachite (2) Nickel steel (C) Calamine (3) Na3AlF6 (D) Cryolite (4) CuCO3.Cu(OH)2 (5) ZnCO3 Column I Column II (A) Pendulum (2)...
Match the items of Column I with the items of Column II
Column I Column II (A) Coloured band (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)...
Match items of Column I with the items of Column II
Column I Column II (A) Cyanide process (1) Ultrapure Ge (B) Froth Floatation Process (2) Dressing of ZnS (C) Electrolytic reduction (3) Extraction of Al (D) Zone refining (4) Extraction of Au ...
Match the items of Column I with the items of Column II
Column I Column II (A) Sapphire (1) Al2O3 (B) Sphalerite (2) NaCN (C) Depressant (3) Co (D) Corundum (4) ZnS (5) Fe2O3 Column I Column II (A) Sapphire (3) Co (B) Sphalerite (4) ZnS (C)...
Match the items of Column I with items of Column II
Column I Column II (A) Blistered Cu (1) Aluminium (B) Blast furnace (2) 2Cu2O + Cu2S → 6Cu + SO2 (C) Reverberatory furnace (3) Iron (D) Hall-Heroult process (4) FeO + SiO2 → FeSiO3 (5) 2Cu2S...
Write the chemical reactions involved in the extraction of gold by the cyanide process. Also, give the role of zinc in the extraction.
Reactions Involved: 4Au(s) + 8CN-(aq) + 2H2O(aq) + O2(g) → 4[Au(CN)2]-(aq) + 4OH-(aq) 2[Au(CN)2]-(aq) + Zn(s) → 2Au(s) + [Zn(CN)4]2- (aq) Role of Zinc in this reaction - Reducing...
Give two requirements for vapour phase refining.
Requirements for vapour phase refining: 1. Metal must react easily with a reagent to produce volatile complex. 2. The complex which is volatile should be easily decomposed and recovered.
Write down the reactions taking place in Blast furnace-related to the metallurgy of iron in the temperature range 500-800 K.
Reactions Involved: 1. 3Fe2O3 + CO → 2Fe3O4 + CO2 2. Fe3O4 + CO → 3FeO + 2CO2 3. Fe2O3 + CO → 2FeO + CO2
How are metals used as semiconductors refined? What is the principle of the method used?
1. Semiconductors are purified by the method of zone refining. 2. The refining of the surface depends on the principle that the impurities are more soluble in molten metal than solid metal. 3. The...
What is the role of flux in metallurgical processes?
Role of flux in metallurgical processes: 1. To remove the gangue, certain substances are mixed with it. These are called fluxes. 2. Flux can be basic or acidic. 3. Flux which is acidic removes basic...
What should be the considerations during the extraction of metals by electrochemical method?
Considerations during the extraction of metals by electrochemical method: 1. The reactivity of the formed metal. 2. Electrodes must be made of suitable materials 3. To form a molten mass, flux is...
Why is an external emf of more than 2.2V required for the extraction of Cl2 from brine?
Reaction involved in the extraction of Cl2 from brine: 2Cl- (aq) + 2H2O(l) → 2OH- (aq) + H2(g) + Cl2(g) Calculation: ΔGᶱ = -nFE° ΔGᶱ = +422kJmol-1. E° = 422x103 / 2×96500 E° = - 2.2V For the...
At temperatures above 1073K coke can be used to reduce FeO to Fe. How can you justify this reduction with the Ellingham diagram?
The ∆G formation of FeO is a bit negative than the ∆G formation of carbon monoxide from carbon. Summation of both ∆G will be negative at about 1073K. Above 1073K the FeO production line exceeds the...
Wrought iron is the purest form of iron. Write a reaction used for the preparation of wrought iron from cast iron. How can the impurities of sulphur, silicon and phosphorus be removed from cast iron?
Limestone can be combined with flux to remove impurities of sulfur, silicon and phosphorus. They form an easily removable slag. The metal is removed from the slag by passing through the rollers....
How is copper extracted from low-grade copper ores?
Copper is extracted by hydrometallurgy method from the copper ores which are low graded. The Cu is treated with cast iron or H2 and is leached out by the acid. Reaction Involved: Cu2 (aq) + H2(g) →...
Write two basic requirements for refining of metal by Mond process and by Van Arkel Method.
1. The metal must react easily with a reagent to produce complex. 2. The complex which is volatile must be easily decomposed and do not give off any additional products and recovery must also be...
Although carbon and hydrogen are better-reducing agents they are not used to reduce metallic oxides at high temperatures. Why?
Carbon and hydrogen will not reduce oxides into metals but will instead build hydrides and carbides. Thus, they are not used as the reducing agents.
How do we separate two sulphide ores by Froth Floatation Method? Explain with an example.
The two sulphide ores competing with coming into the froth can be separated by adjusting the oil to the amount of water or by adding depressants such as NaCN. If we have two sulphide metals, ZnS and...
The purest form of iron is prepared by oxidising impurities from cast iron in a reverberatory furnace. Which iron ore is used to line the furnace? Explain by giving a reaction.
The iron ore which is used to line the reverberatory furnace is Haematite ore (Fe2O3). Example: In the following reaction, Haematite ore forms iron and CO. Fe2O3 + 3 C → 2 Fe + 3CO
The mixture of compounds A and B is passed through a column of Al2O3 by using alcohol as eluant. Compound A is eluted in preference to compound B. Which of the compounds A or B, is more readily adsorbed on the column?
Compound A does not absorb well in the column and moves down the column with alcohol i.e. eluant, while compound B is well absorbed in the column and cannot go down the column.
Why is sulphide ore of copper heated in a furnace after mixing with silica?
The copper sulphide ore is burned in the furnace after mixing with silica because the metal impurities present in it can form slag and silica and will be easily removed. Copper is produced as matte...
Why are sulphide ores converted to oxide before reduction?
The Sulphide ores cannot be easily reduced so they are usually converted to oxides because the oxides can be easily reduced.
Which method is used for refining Zr and Ti? Explain with the equation.
The Van Arkel method is used to filter Zr and Ti. Van Arkel's process involves heating the impure metal with Iodine. It builds a complex structure where it decomposes at high temperatures, restores...
Brine is electrolysed by using inert electrodes. The reaction at anode is ________.
(i) Cl–(aq.) →1/2Cl2 (g) + e– ; E°cell = 1.36V (ii) 2H2O(l) → O2(g0 + 4H+ + 4e- ; E°cell = 1.23V (iii) Na+(aq) + e- → Na(s) ; E°cell = 2.71V (iv) H+(aq) + e- → 1/2H2(g) ; E°cell = 0.00V ...
In the metallurgy of aluminium ________________.
(i) Al3+ is oxidised to Al (s). (ii) 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...
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 Correct Answer: (i) Cu and Zn Explanation: Electrolytic refining is used to purify Copper and Zinc metals.
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....
Choose the correct option of temperature at which carbon reduces FeO to iron and produces CO.
(i) Below temperature at point A. (ii) Approximately at the temperature corresponding to point A. (iii) Above temperature at point A but below a temperature at point D. (iv) Above temperature at...
Below point ‘A’ 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. Correct...
For the reduction of FeO at the temperature corresponding to point D, which of the following statements is correct?
(i) ∆G value for the overall reduction reaction with carbon monoxide is zero. (ii) ∆G value for the overall reduction reaction with a mixture of 1 mol carbon and 1 mol oxygen is positive. (iii) ∆G...
At the temperature corresponding to which of the points in the Figure, FeO will be reduced to Fe by coupling the reaction 2FeO → 2Fe + O2 with all of the following reactions?
(a) C + O2 → CO2 (b) 2C + O2 → 2CO (c) 2CO + O2 → 2 CO2 (i) Point A (ii) Point B (iii) Point D (iv) Point E Correct Answers: (ii) Point B (iv) Point E Explanation: At the temperature...
Which of the following option are correct?
(i) Cast iron is obtained by remelting pig iron with scrap iron and coke using hot air blast. (ii) In the extraction of silver, silver is extracted as cationic complex. (iii) Nickel is purified by...
In the extraction of aluminium by Hall-Heroult process, purified Al2O3 is mixed with CaF2 to
(i) lower the melting point of Al2O3 (ii) increase the conductivity of molten mixture. (iii) reduce Al3+ into Al(s). (iv) acts as a catalyst Correct Answers: (i) lower the melting point of...
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...
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 depressant. (iv) using froth stabilisers. Correct Answers: (ii) adjusting the proportion of oil to water....
Common impurities present in bauxite are ____________.
(i) CuO (ii) ZnO (iii) Fe2O3 (iv) SiO2 Correct Answers: (iii) Fe2O3 (iv) SiO2 Explanation: Common impurities present in bauxite are Fe2O3 and SiO2
Which of the following ores are concentrated by froth flotation?
(i) Haematite (ii) Galena (iii) Copper pyrites (iv) Magnetite Correct Answers: (ii) Galena (iii) Copper pyrites Explanation: Galena and Copper pyrites are the ores which can be concentrated...
Which of the following reactions occur during calcination?
(i) CaCO3→CaO+CO2 (ii) 4FeS2+11O2→2Fe2O3+8SO2 (iii) 2Al(OH)3→Al2O3+3H2O (iv) Cu2S+2CuO→4Cu+SO2 Correct Answers: (i) CaCO3→CaO+CO2 (iii) 2Al(OH)3→Al2O3+3H2O Explanation:...
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 Correct Answers: (i) haematite (ii) calamine Explanation: Haematite and Calamine are the calcined ores which gets reduced by...
The main reactions occurring in the blast furnace during the extraction of iron from haematite are ________.
(i) Fe2O3 + 3CO → 2Fe + 3CO2 (ii) FeO + SiO2 → FeSiO3 (iii) Fe2O3 + 3C → 2Fe + 3CO (iv) CaO + SiO2 → CaSiO3 Correct Answers: (i) Fe2O3 + 3CO → 2Fe + 3CO2 (iv) CaO + SiO2 → CaSiO3 Explanation:...
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. Correct Answers: (i) heating with a stream of carbon monoxide (ii) heating with...
Which of the following statements are correct?
(i) A depressant prevents a certain type of particle to come to the froth. (ii) Copper matte contains Cu2S and ZnS. (iii) The solidified copper obtained from the reverberatory furnace has blistered...
In the extraction of chlorine from brine _____________.
(i) ΔG° for the overall reaction is negative. (ii) ΔG° for the overall reaction is positive. (iii) E° for the overall reaction has a negative value. (iv) E° for the overall reaction has a positive...
In the extraction of chlorine by electrolysis of brine ____________.
(i) oxidation of Cl– ion to chlorine gas occurs. (ii) reduction of Cl– ion to chlorine gas occurs. (iii) For the overall reaction, ∆Gᶱ has a negative value. (iv) a displacement reaction takes place....
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) Correct...
Which of the following reactions is an example of autoreduction?
(i) Fe3O4 + 4CO → 3Fe + 4CO2 (ii) Cu2O + C → 2Cu + CO (iii) Cu2+ (aq) + Fe (s) → Cu (s) + Fe2+ (aq) (iv) Cu2O + 1/2Cu2S → 3Cu + 1/2SO2 Correct Answer: (iv) Cu2O + 1/2Cu2S → 3Cu + 1/2SO2...
A number of elements are available in earth’s crust but most abundant elements are ____________.
(i) Al and Fe (ii) Al and Cu (iii) Fe and Cu (iv) Cu and Ag Correct Answer:(i) Al and Fe Explanation: The most abundant elements in the earth's crust are Aluminium (8.1 %) and Iron...
In the extraction of copper from its sulphide ore, the metal is formed by the reduction of Cu2O with
(i) FeS (ii) CO (iii) Cu2S (iv) SO2 Correct Answer: (iii) Cu2S Explanation: Reaction Involved - 2Cu2S+3O2 →2Cu2O+2SO2 2 Cu2O+ Cu2S →6Cu+ SO2
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...