How is 'cast iron' different from 'pig iron'?

Native silver metal forms a water soluble complex with a dilute aqueous solution of $NaCN$ in the presence of

In the Goldschmidt thermite process,which substance acts as the reducing agent?

Copper matte is a mixture of

From argentite $(Ag_2S)$ ore,the method used in obtaining metallic silver is:

Consider the following metallurgical processes:
$(i)$ Heating impure metal with $CO$ and distilling the resulting volatile carbonyl (boiling point $43\,^{\circ}C$) and finally decomposing at $150\,^{\circ}C$ to $200\,^{\circ}C$ 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 sulphide.
$(iii)$ Electrolysing the molten electrolyte containing approximately equal amounts of the metal chloride and $CaCl_2$ to obtain the metal.
The processes used for obtaining sodium,nickel and copper are,respectively,