91. Give reasons:
(i) Zinc and not copper is used for the recovery of silver from the complex [Ag (CN)₂]^–

(ii) Pine oil is generally added in the froth floatation process.

(iii) Graphite is used as anode but not diamond.

(iv) In the metallurgy of iron, lime stone is added to the ore.

(v) Reduction of metal oxides by aluminium becomes faster just after ignition of mixture.

92.

Explain different methods of reduction of the roasted/calcined ore to the metallic form.

93. Describe the methods, generally used to refine metals.

94.

The impurities present in minerals are called ______________.

95.

Cassiterite is an ore of ___________.

96.

Calamine is an ore of ________.

97.

Aluminium is obtained from Al₂O₃ by_________reduction.

98.

In the metallurgical process for the electrorefining of the metal the anode is made of _________ metal.

99.

In the Bessemer converter during the extraction of copper, the substance responsible for forming blister is  ___________.

100.

During the extraction, the metallic silver is precipitated by the addition of __________ to ________