Metal above in activity series are more reactive and can displace the less reactive metal.(i) $\mathrm{NaCl}$ solution and copper metal$\mathrm{Na}$ is more reactive than $\mathrm{Cu}$, thus it will not give displacement reaction.(ii) $\mathrm{AgNO}_3$ solution and copper metal.$\mathrm{Ag}$ can be replaced by $\mathrm{Cu}$ as it is above silver in the reactivity series. Therefore, this pair will give displacement reaction.(iii) $\mathrm{Al}_2(\mathrm{SO}_4)_3$ solution and magnesium metal. Magnesium is more reactive than aluminium hence displacement reaction will occur and Magnesium sulphate is formed.(iv) $\mathrm{ZnSO}_4$ solution and iron metalThe 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.