CBSE Important Questions Class 12 Chemistry Chapter 6

Important Questions Class 12 Chemistry Chapter 6

Important Questions for CBSE Class 12 Chemistry Chapter 6 – General Principles and Processes of Isolation of Elements

Extramarks Important Questions Class 12 Chemistry Chapter 6 helps students ace their exam preparations. By referring to these questions, students will get an idea of the marks distribution, numerals, terminologies and concepts related to Chapter 6 “General Principles and Processes of Isolation of Elements”. Chapter 6 Class 12 Chemistry Important Questions prepared by Extramarks subject matter experts will help students gain an in-depth understanding of the above-mentioned topics. 

These questions are concise and are created in accordance with the CBSE Syllabus. Chemistry Class 12 Chapter 6 Important Questions are presented with step-by-step solutions. Students can refer to these CBSE questions from the Extramarks website. This set is put together by subject matter experts in a comprehensive manner, making it easier for students to focus on and retain the important concepts of the chapter.  

CBSE Class 12 Chemistry Chapter 6 Important Questions

Study Important Questions for Class 12 Chemistry Chapter 6 – General Principles and Processes of Isolation of Elements

A few of the Important Questions Class 12 Chemistry Chapter 6 are discussed below. Students can access the link provided to access the full set of Important Questions. 

Very Short Answer Questions.                                                                                                       
1 Mark

Q1. State the reaction engaged in the extraction of copper from low-grade ores.

Ans. Hydrometallurgy is used to extract copper from low-grade ores. Acid or bacteria is usually used to leach it out. The solution that comprises Cu2+ is tended with scrap iron or H2 .

The equation we derive is :

Cu2+aq+H2gCu pure+2H+

Q2. Write down the constituents of German silver.

Ans. German silver includes constituents such as 

Cu25-30%, Zn25-30%,and Ni40-50%.  

Q3. Write the composition of the molten mixture which is electrolysis to extract aluminium.

Ans. The electrolysis of molten  Cryolite’s composition to extract aluminium is  

Al2O3+Na3AlF6 or CaF2 .

Q4. Which method of purification is represented by the following reaction?

                        523K           1700K

  Ti+2I2g ⟶ TiI4g ⟶ Tis+2I2g

Ans. The following method represents the Van Arkel process which is used for refining zirconium or titanium.

Q5. List down the impurities present in the bauxite ore.

Ans.  SiO2, Fe2O3, TiO2  are the impurities existent in bauxite ore.

Q6. Give the names and formulae of three ores that are concentrated by the froth floatation process.

Ans. The names and the formula of the three ores concentrated by the froth floatation method are as follows:- 

1)  Cinnabar – HgS

2)  Galena – PbS

3)  Zinc blende – ZnS

Q7. What is the composition of copper matte?

Ans. Copper matte is composed of Cu2S and FeS.

Q8. Although aluminium is above hydrogen in the electrochemical series, it is stable in air and water. Why? 

Ans. Due to the formation of inert oxide Al2O3, even when aluminium is above hydrogen in the electrochemical series still it is stable in air and water.

Q9. Out of Fe, Cu, Al and Pb, which metal (s) cannot be attained by smelting.

Ans. The metal that can not be obtained by smelting is Aluminum.

Q10. Carbon and hydrogen are better-reducing agents, yet they are not used to reduce metallic oxides at high temperatures. Why?

Ans. Carbon and hydrogen react with metals at high temperatures creating carbides and hydrides. Therefore, carbon and hydrogen are not used to reduce metallic oxides at high temperatures.

Q11. What is the thermodynamic criteria for the feasibility of a reaction? 

Ans: The Gibbs free energy must be negative is the only thermodynamic criterion for the feasibility of a reaction. 

Short Answer Questions.                                                                                                               
2 Marks

Q1. Extraction of copper directly from sulphide ore is less favourable than from its oxide through reduction. Explain.

Ans. The reactions are as follows 

    2Cus+CsCS2s+2Cus

     CuOs+CsCOg+Cug

In the latter reaction, Gibbs free energy is more negative than the former so the process is more simple and occurs instantly. 

Q2. Write the chemical reactions taking place in different zones in the blast furnace for the extraction of iron from its ore.

Ans. The chemical reactions taking place in different zones in the blast furnace for the extraction of iron from its ore are as follows:

3Fe2O3+CO2Fe3O4+CO2

Fe3O4+4CO 3Fe+ 4CO2in the temperature range of 500-800K

Fe2O3+CO 2Fe+CO2

C+CO2 2CO

FeO+CO Fe+CO2 in the temperature range of 900-1500K 

Q3. How is pure copper extracted from its principal ore? Write the chemical reactions occurring during the extraction.

Ans. The chemical reactions by which pure copper is extracted from its principal ore is represented below:

2CuFeS2+O2Cu2S+2FeS+O2

Cu2S+3O22Cu2O+2SO2

Cu2O+C2Cu+CO

2Cu2O+Cu2S6Cu+SO2

Q4. What is pyrometallurgy? Give a suitable example.

Ans. Pyrometallurgy is the process of reduction of a metal oxide by heating with coke or another reducing agent like aluminium, magnesium, etc.

                  975K

ZnO+C ⟶ Zn+CO

Q5. Give equations for the industrial extraction of zinc from calamine.

Ans. The equation for the industrial extraction of zinc from calamine is stated below:

ZnCO3⟶ ZnO+CO2calcination

ZnO+C ⟶Zn+COreduction

Q6. Name the method of refining the below-mentioned metals –

(a) Sn

(b) Hg 

(c) Ni 

(d) Cu 

(e) Ge

(f) Zr

Ans. The method of refining the metals is as follows:

(a) Liquation

(b) Distillation

(c) Mond process

(d) Electrolytic refining

(e) Zone refining

(f) Van Arkel process

Q7. How are impurities separated from bauxite ore to get pure alumina? 

Ans. The impurities are separated from bauxite ore to get alumina by the leaching process. The reaction is as follows

Al2O3s+2NaOHaq+3H2Ol⟶ 2NaAlOH4aq

2NaAlOH4aq+CO2aq⟶Al2O3xH2Os+2NaHCO3aq

Al2O3xH2Os⟶Al2O3s+xH2Og(alumina)

Q8. Name the process for the benefaction/concentration of (i) an ore having lighter impurities and (ii) sulphide ore. (Chapter 6 class 12 chemistry important questions)

Ans: 

(i) Gravity separation is the process of concentration of ore having lighter impurities.

(ii) Froth floatation is the process of concentration of sulphide ore.

Conclusion:

The Class 12 Chemistry Chapter 6 Important Questions are comprehensive and designed to solve the doubts of the Class 12 students. They can quickly revise these concepts and gain insight into this chapter. This set of questions includes all the significant questions and related equations of General Principles and Processes of Isolation of Elements.

FAQs (Frequently Asked Questions)

1. How are metals used as semiconductors refined? What is the principle of the method used?

Metals of high grade like germanium, silicon, etc., used as semiconductors are refined by the zone refining method.

Principle: This method is based upon the principle that impurities are more soluble in the molten state of metal than in the solid state.

2. What should be taken into account when extracting metals using an electrochemical process?

The considerations that need to be contemplated during the extraction of metals by the electrochemical method are given below

  1. Reactivity of the metal produced
  2. Electrodes should be made out of suitable material
  3. Insertion of flux for creating molten mass conducting

3. Why is sulphide ore of copper heated in a furnace after mixing with silica?

Iron oxide is present as an impurity in sulphide ore of copper forms slag, which is an iron silicate, and copper is produced in the form of copper matte.

FeO+SiO2⟶FeSiO3

4. Write the chemical reactions involved in the extraction of gold by the cyanide process. Apart from that, give the role of zinc in the extraction.

Gold ores are leached with sodium cyanide solution in the presence of air. Due to oxidation, gold dissolves in sodium cyanide forming a complex. The chemical reaction can be expressed as follows:- 

8NaCN+4Au+2H2O+O2⟶ 4NaAuCN2+4NaOH

The metal is recovered by displacement method by adding zinc.

2NaAuCN2+Na2ZnCN2+2Au

5. Why should students of class 12 refer to extra questions for Class 12 Chemistry Chapter 6 Solutions?

Class 12 is an important academic year for every student. Therefore, students should keep practising the past years’ papers as well as Extra Questions for their board exams. Class 12 Chemistry Chapter 6 Important Questions will be beneficial for CBSE Class 12 students to score excellent marks in their board exams. These notes consist of the important topics from Chapter 6 of Class 12 Chemistry, which will aid students to get a thorough understanding of the chapter and help them clear their doubts. These Class 12 Chemistry Chapter 6 Important Questions are made in accordance with the CBSE syllabus.