Which of the ores of aluminium, iron, copper and zinc could be concentrated by magnetic method?

2

(a)

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

2

(a)

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

2

(a)

Name a sulphide ore which is not concentrated by froth flotation process.Why is it so?

2

(a)

Describe the principle controlling each of the following processes.
(i) Vapour phase refining of titanium metal.
(ii) Froth floatation method of concentration of a sulphide ore.

2

(a)

Describe the principle controlling each of the following processes :
(i) Preparation of cast iron from pig Iron.
(ii) Preparation of pure alumina (Al₂O₃) from bauxite ore.

2

(a)

How does NaCN act as a depressant in preventing zinc from forming the froth? Explain.

2

(a)

Why thermite process is not used for obtaining aluminum from bauxite.

2

(a)

Write two basic requirements for refining of a metal by Monds process and by van Arkel method.

2

(a)

Although carbon and hydrogen are better reducing agents but they are not used to reduce metallic oxides at high temperatures, why?

2

(a)

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

2

(a)

Give two requirements for vapour phase refining.

2

(a)