JEE Questions for Chemistry General Principles And Processes Of Isolation Of Elements Quiz 4 - MCQExams.com

A molten mixture of Al₂O₃ and Na₃AlF₆ is used as an electrolyte in the commercial electrochemical process for extraction of Al.

As the reduction potential of hydrogen is lower than that of sodium, it will be discharged at the cathode and chloride will be discharged at the anode.

SnO₂ (tin stone) is also called cassiterite.

Electrolysis of aqueous solution of NaCl (brine) gives Cl₂ at the anode

Galena (PbS) is an ore of Pb.

Ag is leached by cyanide process.

The common method of extraction of metals from oxide ores is carbon reduction method.

Pyrolusite is an oxide ore which is not concentrated by froth floatation method.

Roasting removes Sulphur from an ore in presence of oxygen as SO₂ gas

Copper sulphate activates the floating character of sulphide ore (ZnS).

FeO.Cr₂O₃ is magnetic which is separated by magnetic separation method from ore of tin (non-magnetic).

Potassium ethyl xanthate acts as a collector. KCN and NaOH depress the floatation property of ZnS and FeS₂ particles. Thus, only PbS particles go into the froth. Now copper sulphate is added to the tank (mixture) which activates floating character of ZnS and this time only ZnS comes along with froth. The remaining slurry is acidified and FeS₂ floats alongwith froth.

PbS is good conductor and ZnS is poor conductor of electricity.

Wolframite is ferrous tungstate FeWO₄ which is magnetic in nature.

Calamine is ZnCO₃ and zincite is ZnO. Both are minerals of zinc.