Samples of four m

(i) Metal B gives the displacement reaction with the iron (II) sulphate, hence it is the most reactive metal.

(ii) When metal B is added to copper (II) sulphate solution, it displaces the copper.

(iii) Metal B is the most reactive metal whereas metal D is the least reactive metal as it cannot displace any metal from its salt solution. Hence, the decreasing order of reactivity of the metals is:

B > A > C > D.