Metal above in activity series are more reactive and can displace the less reactive metal.
(i) NaCl solution and copper metal
Na is more reactive than Cu, thus it will not give displacement reaction.
(ii) AgNO3 solution and copper metal.
Ag can be replaced by Cu as it is above silver in the reactivity series. Therefore, this pair will give displacement reaction.
(iii) Al2(SO4)3 solution and magnesium metal. Magnesium is more reactive than aluminium hence displacement reaction will occur and Magnesium sulphate is formed.
(iv) ZnSO4 solution and iron metal
The displacement reaction does not occur because iron metal is less reactive than zinc metal. So, a less reactive iron metal cannot displace a more reactive zinc metal from zinc sulphate solution.