Give reasons for the following :
(i) Metals can be recovered from their ores by chemical methods.
(ii) High purity metals can be obtained by zone refining method.
(iii) Why is sodium choride added during electrolysis of fused anhydrous magnesium chloride ?
(iv) Why is chalcocite roasted and not calcinated during recovery of copper ?

Why sodium chloride is added during electrolysis of fused anhydrous magnesium chlroride?

Outline the principels of refining of metals by the following methods : (i) Distillation (ii) Zone refining (iii) Electrolysis.

Explain the following (i) Chalcocite is roasted and not calcined during recovery of copper. (ii) Magnesium oxide is used for lining in steel making furnace

Give the correct order of initials T or F for following statements. Use T if statement is true and F if it is false. (i) Every mineral is an ore but every ore is not a mineral (ii) Slag is product formed during extraction of metal by combination of flux and impuritites. (iii) Highly pure metals can be obtained by zone refining. (iv) Carnallite is an ore of magnesium and sodium.

Assign suitable terms to the following : (i) Materials which can withstand very high temperatures without melting and softening. (ii) Sulphide ores are generally heated in a stream of air. (iii) The substances used for the removal of gangue in the ores in the form of slags. (iv) Two metals which are manufactured by the electrolysis of their fused salts. (v) Two metals used for reduction in metallurgical processes.

(a) Name the method of refining which is (i) used to obtain semiconductor of high purity (ii) used to obtain low boiling metal. (b) Write chemical reactions taking place in the extraction of copper from Cu_(2)S .

Match the following processes of metallurgy with their corresponding ore for which they are used : (i) Froth floatation method (a) Germanium (ii) Electrolytic refining of metals (b) ZnS (iii) Zone refining of metals (c) copper

(i) Name the most common ore of the metal aluminum from which the metal is extracted. Write the chemical formula of the ore. (ii) Name the process by which impure ore of aluminum gets purified by using concentrated solution of an alkali. (iii) Write the equation for the formation of aluminum at the cathode during the electrolysis of alumina.

Select from the given below (A to F), the one substance in each case which matches the descriptions given in parts (i) to (vi). Copy and complete the given grid with your answers as shown for part (i). (A) Ammonia (B) Copper oxide (C) Copper sulphate (D) Hydrogen chloride (E) Hydrogen sulphide (F) Lead bromide (i) Although this compound is not a metal hydroxide, its aqueous solution is alkaline in nature. (ii) A solution of this compound is used as the electrolyte when copper is purified. (iii) When this compound is electrolysed in the molten state, lead is obtained at the cathode. (iv) This compound can be oxidized to chlorine. (v) This compound smells of rotten eggs. (vi) This compound can be reduced to copper when heated with coke.

Minerals from which metals can be extracted economically and easily are called ores.The extraction of metals from theirs ores involves the following processes. (i)Concentration. (ii)Calcination | roasting | leaching . (iii)Reduction. It is carried out be one of the following methods. Which of the following reactions reactions does not occur in Bessemer converter in the extraction of copper from chalcopyrites ?