Which of the following options are correct?
 

Cast iron is purest form of iron than pig iron. The iron obtained from blast furnace contains about 4% carbon and many impurities in the smaller amount is known as pig iron. Cast iron is obtained by remelting pig iron with scrap iron and coke using hot air blast.

Silver is extracted from its native ore by leaching. Silver is extracted as anionic complex, ${[\mathrm{Ag}{\left(\mathrm{CN}\right)}_2]}^{-}$.

Nickel is purified by Mond process.