In the alumino-thermite process $Al$ act as

Consi der the following metallurgical processes

$(I)$ Heating impure metal with $CO$ and distilling the resulting volatile carbonyl (b.p. $43\,^oC$ ) and finally decomposition at $150^o-200\,^oC$ to get the pure metal

$(II)$ Heating the sulphide ore in air until a part is converted to oxide and then further heating in the absence of air to let the oxide react with unchanged metal sulphide

$(III)$ Electrolysis of the molten electrolyte containing approximately equal amounts of the metal chloride and $NaCl$ to obtained the metal

The processes used for obtaining magnesium, nickel and copper are respectively

The form of iron obtained from blast furnace is

Froth floatation process is used for the concentration of the ore of

Which of the reaction is suitable for concentrating ore by leaching process?