Find the total number of feasible reaction which would yeild free metal.
(a) `HgS+O_(2) underset(Delta)overset(600^(@)C)to Hg+SO_(2)`
(b) `HgS+2HgO overset(Delta)to 3Hg+SO_(2)`
(c ) `CuSO_(4)+3CO to 3Cu+2SO_(2)`
(d) `Fe_(2)O_(3)+3CO overset(Delta)to 2Fe+3CO_(2)`
(e) `Fe_(2)O_(3)+3C overset(Delta)to 2Fe+3CO`
(f) `ZnSO_(4)+2C overset(Delta)to Zn+SO_(2)+2CO`
(g) `4Cu_(2)O+CH_(4) to 8Cu+2H_(2)O+CO_(2)`
(h) `2Na[Au(CN)_(2)]+Zn to Na_(2)[Zn(CN)_(4)]+2Au`

Answer

7

Explanation

a,b,c,d,e,g,h
f `ZnSO_(4)+2C overset(Delta)to ZnS+4CO`