Question
Metals A, B, C, D, and E were placed in sulfate solutions.
(a) The results are given where √ = reaction occurred and ✘ = no reaction.
(i) Identify the oxidation state of metal A in \(ASO_4\).
(ii) Deduce the activity series of the metals.
(b) Sketch the voltaic cell that produces the greatest electromotive force, EMF, using the information in part (a). Label the direction of electron flow, salt bridge, anode, cathode, the metals (A–E) and solutions used in each half-cell.
(c) Deduce one metal that could be electroplated, with high efficiency, on to a metal key using an aqueous salt of the metal. Use section 24 of the data booklet.
Answer/Explanation
Answer:
(a) (i) +2/II
(ii) C A B D E
(b) 
two half cells with electrodes, solutions, salt bridge and connecting wire
C as anode AND E as cathode
\(CSO_4\) AND \(ESO_4\) «solutions» labelled
electron flow shown «on wire» from more reactive to less reactive metal
(c) copper/Cu OR silver/Ag