Find the number of metals which are commercially reduced by self-reduction from the given metals :
`Fe, Al, Z, Sn, Pb, Hg, Cu`.

Find the number of metals which are commercially reduced by self-reduction from the gives metals Ag, Cr, Mn, Sn, Zn, Fe

Find the number of metals which are reduced by self-reduction from the given metals: Fe,Al,Zn,Sn,Pb,Hg,Cu

Find the number of metals which are commercially reduced by carbon reduction method from the given metals : Ag, Cr, Mn, Sn, Zn, Fe .

Find the number of metals which are commercially by carbon reduction method from the given metals : Ag, Cr, Mn, Sn, Zn, Fe .

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

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

How many metals are commercially extracted by hydrometallurgy from the given metals : Ag, Mn, In, Cr,Pb,Au .

How many metals are commercially extracted by hydrometallurgy from the given metals : Ag, Mn, In, Cr,Pb,Au .

How many metals are commercially reduced by Goldschmidt's aluminothermic process from the given metals ? Na, Pb, Al, Mn, Sn .

How many metals are commercially reduced by Goldschmidt's aluminothermic process from the given metals ? Na, Pb, Al, Mn, Sn .