# NCERT solutions Chemistry Textbook for Class 12 Part 1 chapter 6 General Principles and Processes of Isolation of Elements

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### Chapter 6 - General Principles and Processes of Isolation of Elements

#### Pages 150 - 157

Which of the ores mentioned can be concentrated by magnetic separation method?

Q 1 | Page 150 | view solution

What is the significance of leaching in the extraction of aluminium?

Q 2 | Page 150 | view solution

The reaction, Cr_2O_3 + 2Al -> Al_2O_3 + 2Cr   (triangleG^theta = -421 kJ) is thermodynamically feasible as is apparent from the Gibbs energy value.  Why does it not take place at room temperature?

Q 3 | Page 157 | view solution

Is it true that under certain conditions, Mg can reduce SiO2 and Si can reduce MgO? What are those conditions?

Q 4 | Page 157 | view solution

#### Pages 163 - 164

Copper can be extracted by hydrometallurgy but not zinc. Explain.

Q 1 | Page 163 | view solution

What is the role of depressant in froth floatation process?

Q 2 | Page 163 | view solution

Why is the extraction of copper from pyrites more difficult than that from its oxide ore through reduction?

Q 3 | Page 163 | view solution

Explain: Zone refining

Q 4.1 | Page 163 | view solution

Explain Column chromatography.

Q 4.2 | Page 163 | view solution

Out of C and CO, which is a better reducing agent at 673 K?

Q 5 | Page 163 | view solution

Name the common elements present in the anode mud in electrolytic refining of copper. Why are they so present ?

Q 6 | Page 163 | view solution

Write down the reactions taking place in different zones in the blast furnace during the extraction of iron.

Q 7 | Page 163 | view solution

Write chemical reactions taking place in the extraction of zinc from zinc blende.

Q 8 | Page 163 | view solution

State the role of silica in the metallurgy of copper.

Q 9 | Page 163 | view solution

What is meant by the term “chromatography”?

Q 10 | Page 163 | view solution

What criterion is followed for the selection of the stationary phase in chromatography?

Q 11 | Page 163 | view solution

Describe a method for refining nickel.

Q 12 | Page 164 | view solution

How can you separate alumina from silica in bauxite ore associated with silica? Give equations, if any

Q 13 | Page 164 | view solution

Giving examples, differentiate between ‘roasting’ and ‘calcination’.

Q 14 | Page 164 | view solution

How is 'cast iron' different from 'pig iron'?

Q 15 | Page 164 | view solution

Differentiate between “minerals” and “ores”.

Q 16 | Page 164 | view solution

Why copper matte is put in silica lined converter?

Q 17 | Page 164 | view solution

What is the role of cryolite in the metallurgy of aluminium?

Q 18 | Page 164 | view solution

How is leaching carried out in case of low grade copper ores?

Q 19 | Page 164 | view solution

Why is zinc not extracted from zinc oxide through reduction using CO?

Q 20 | Page 164 | view solution

The value of triangle_tG^theta for formation of Cr2Ois − 540 kJmol−1 and that of Al2 O3 is − 827 kJmol−1. Is the reduction of Cr2O3 possible with Al?

Q 21 | Page 164 | view solution

Out of C and CO, which is a better reducing agent for ZnO ?

Q 22 | Page 164 | view solution

The choice of a reducing agent in a particular case depends on thermodynamic factor. How far do you agree with this statement? Support your opinion with two examples.

Q 23 | Page 164 | view solution

Name the processes from which chlorine is obtained as a by-product. What will happen if an aqueous solution of NaCl is subjected to electrolysis?

Q 24 | Page 164 | view solution

What is the role of graphite rod in the electrometallurgy of aluminium?

Q 25 | Page 164 | view solution

Explain the principle of the method of electrolytic refining of metals. Give one example.

Q 26 | Page 164 | view solution

Outline the principles of refining of metals by the following methods:  Vapour phase refining

Q 27 | Page 164 | view solution

Predict conditions under which Al might be expected to reduce MgO.

Q 28 | Page 164 | view solution