NCERT Class 12 Chemistry Optional Questions with Answers
41 Electrolytic reduction of Al2O3 to Al by Hall- Herault process is carried out
Answer: in presence of cryolite which forms a melt with lower melting point.
42 The chemical composition of ‘slag’ formed during the melting process in the extraction of copper is
46 The method of zone refining of metals is based on the principle of
Answer: greater solubility of the impurity in the molten state than in the solid.