The set-up shown was used to compare the reactivity of four metals, P, Q, R and S. Metal strips P, Q. R and S and a copper plate were first cleaned with sandpaper. Each metal strip was then clipped onto the wet ﬁlter paper and the voltmeter reading was recorded.A summary of the voltmeter readings obtained is shown in the table below.(a) Give a reason why the metal strips and copper plate must first be cleaned
(b) From the results in the table,
(i) arrange the metals. P, Q, R, S in order of increasing reactivity.
(ii) state how the positions of the metals in the reactivity series affect the magnitude of voltage.
(c)(i) Given that R is an element in Group II of the Periodic Table, what is
observed if it is placed in copper(ll) sulfate solution?
(ii) Write an ionic equation for the reaction.
(d) State and explain any difference in the voltmeter readings if the experiment is repeated using filter paper soaked with organic solvent methylbenzene.