In the commercial electrochemical process for aluminium extraction, the electrolyte used is

Options

A. `Al(OH)_3` in NaOH solution
B. An aqueous solution of `Al_2(SO_4)_3`
C. A molten mixture of `Al_(2)O_3` and `Na_(3)AlF_6`
D. A motlen mixture of `Al_(2)O_3 ` and `Al(OH)_3`

Answer

C

Explanation

Lead is mainly extracted from galena (PbS). The metallic sulphides like `Cu_(2)S`, PbS, HgS, `Sb_(2)S_(3)` etc., when heated strongly in free supply of air and `SiO_2` (roasting ) get reduced directly to free metal .This is called auto reduction or self reduction.
`2PbS + 3O_2` `rarr` 2PbO + `2SO_4` ,
2PbO + PbS `rarr` 3Pb + `SO_2`
Tin is generally from tin stone. Metal is obtained by carbon reduction process.
`SnO_(2) + 2C overset(Delta)toSn+2COuarr`