How many of the following metals can be extracted by auto - reduction ?
`Fe, Zn, Pb, Al, Hg, Cu, K, Ca`

Which of the following metals is extracted by auto reduction?

How many of the following metals is extracted by self reduction process? Pb,Au,Mg,Sn,Fe,Al,Ag,Hg,Na,Zn,Cu,Ca

How many of the following metals can be refined by vapour phase refining ? Zn,Zr,Hg,Cd,Ni,Ti,Co,Pt,Fe .

How many of the following metals can be refined by vapour phase refining ? Zn,Zr,Hg,Cd,Ni,Ti,Co,Pt,Fe .

Which of the following metals cannot be extracted by the smelting process ? Al, Zn, Fe and Pb .