Class 12 Chemistry NCERT Exemplar Solutions General Principles & Processes of Isolation of Elements
Download the comprehensive, precise and free solutions for all the NCERT Exemplar Problems of CBSE Class 12 Chemistry Chapter- General Principles and Processes of Isolation of Elements. All the solutions are explained in the simplest and appropriate way.
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Few problems along with their solutions from this chapter are given below:
Q. Zone refining is based on the principle that
(a) impurities of low boiling metals can be separated by distillation.
(b) impurities are more soluble in molten metal than in solid metal.
(c) different components of a mixture are differently adsorbed on an adsorbent.
(d) vapours of volatile compound can be decomposed in pure metal.
Ans. (b) impurities are more soluble in molten metal than in solid metal.
Zone refining is based on the principal that the impurities are more soluble in molten state than in solid state of the metal. A circular mobile heater is fixed at one end of impure metal rod. The molten zone moves along with heater which is moved forward.
As the heater moves forward, the pure metal crystallises out of the melt and the impurities pass on into adjacent molten zone.
At one end, impurities get concentrated. Metals like germanium, silicon, gallium, etc., are refined by this method.
Q. For the reduction of FeO at the temperature corresponding to point D, which of the following statements is correct?
(a) DG value for the overall reduction reaction with carbon monoxide is zero.
(b) DG value for the overall reduction reaction with a mixture of 1 mol carbon and 1 mol oxygen is positive.
(c) DG value for the overall reduction with a mixture of 2 mol carbon and 1 mol oxygen will be positive.
(d) DG value for the overall reduction reaction with carbon monoxide is negative.
Ans. (a) DG value for the overall reduction reaction with carbon monoxide is zero
At point D, DG curve for formation of CO2 from CO and FeO from Fe intersect each other. Therefore, overall reduction of FeO with CO is zero .
Hence, (a) is the correct choice.
Q. Which of the following statements is correct about the role of substances added in the froth floatation process?
(a) Collectors enhance the non-wettability of the mineral particles.
(b) Collectors enhance the wettability of gangue particles.
(c) By using depressants in the process two sulphide ores can be separated.
(d) Froth stabilisers decrease wettability of gangue.
Answer. (a, c)
Froth floatation process is used to extract metal from sulphide ore. This method utilises collectors and depressants whose functions are as follows:
(i) Collectors enhance the non-wettability of the mineral particles.
(ii) By using depressants in the process two sulphide ores can be separated, e.g., sodium cyanide is used as a depressant to separate lead sulphide ore from zinc sulphide ore.
Q. What is the role of flux in metallurgical processes?
Ans. Role of flux in metallurgical process:
(i) Flux is used to remove the gangue by combining with it. Thus, slag formation takes place.
(ii) It makes the molten mass more conducting.
Find below the links to download Class 12 Chemistry NCERT Exemplar Solutions for chapter 6- General Principles and Processes of Isolation of Elements:
Link to Download Solutions
Multiple Choice Questions (Type-I)
Multiple Choice Questions (Type-II)
Short Answer Type Questions
Matching Columns Type Questions
Assertion and Reason Type Questions
Long answer types questions
Class 12 Chemistry NCERT Exemplar Problems: General Principles and Processes of Isolation of Elements
NCERT Exemplar problems are the best source to practice the critical questions like Higher Order Thinking Skill (HOTS) questions. Every year, many questions from the NCERT Exemplar are directly asked in the board exams. Also, these are the kind of questions asked in the various competitive exams and Olympiad level tests. So, it’s very important for students to practice the NCERT exemplar problems to prepare well for the boards and the competitive exams.
Important topics discussed in Class 12 Chemistry chapter – General Principles and Processes of Isolation of Elements, are:
- Occurrence of metals
- Concentration of ores
- Hydraulic washing
- Magnetic separation
- Froth floatation method
- Extraction of crude metal from concentrated ore
- Thermodynamic principles of metallurgy
- Electrochemical principles of metallurgy
- Oxidation reduction
- Uses of aluminium, copper, zinc and iron.
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