(i). Which of the following oxides is reduced by hydrogen?
`MgO,CuO` and `Na_(2)O`
(ii). Which of the following oxides will decompose on heating ?
ZnO, CuO, MgO, and `Ag_(2)O`
(iii). The value of `E_(OX)^(@)` for electrode reaction.
`FetoFe^(2+)+2e^(-)" "CutoCu^(2+)2e^(-)` and `ZntoZn^(2+)+2e^(-)`
are 0.444, `-0.337` and `0763` volt respectively. State which of these metals can replace the orther two from the solution of their salts?

Answer

(i). `CuO`
Cu is below hydrogen in series, so it can reduce from CuO to Cu.
(ii). `Ag_(2)O`
Lower in series stability of oxide become lesser.
(iii). Lower S.R.P. metal can displace higher S.R.P metals ions from solution.