Which of the ores mentioned in Table 6.1. could be concentrated by magnetic separation method?
Table 6.1 Principal ores of some important metal.

2.

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

The reaction.
Cr₂O₃ + 2Al → Al₂O₃ + 2Cr                  (ΔG° = – 421 kJ)
is thermodyanmically feasible as is apparent from the Gibbs energy value. Why does it not take place at room temperature?

Is it true that under certain conditions. Mg can reduce Al₂O₃ and Al can reduce MgO? What are those conditions?

Titanium is a metal of modern times. It is obtained as oxide. Why it could not be extracted earlier despite its wide occurence?

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

State the role of silica in the metallurgy of copper.

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

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