Question

How many metals are commercially purified by electrolysis methods from the given metals?
Na, Al, Pb, Ni

Answer 1

Metals that are commercially purified by electrolysis methods are those metals that cannot easily go through reduction.

Electrolysis methods are for only those metals that are highly electropositive.

$NaCl\to$ highly reactive, done through electro refining .

$A{l}_2{O}_3\to$ cannot go for reduction. As it is more electropositive element. Done through electrorefining.

$PbO+PbS\to Pb+S{O}_2$

Hence, Pb does not follow the electrolysis method.

$NiC{l}_2+Zn\to ZnC{l}_2+Ni$

Hence, Ni does not follow the electrolysis method.

$\therefore$ Electrolysis is done only in two metals that are Na and Al.

Hence, the answer is 2.