A) Electrolysis is the process of decomposing an ionic compound (electrolyte) into its constituent elements by passing an electric current through it, usually in a molten state or in solution.

4. a) Electrolysis is the process of decomposing an ionic compound (electrolyte) into its constituent elements by passing an electric current through it, usually in a molten state or in solution.

4. b) The anode is the electrode connected to the positive terminal of the power supply. In the given diagram, the anode is the right-hand electrode.

4. c) At the anode, oxidation occurs. Chloride ions ($Cl^-$) lose electrons to form chlorine gas.

$$2Cl^-(l) \longrightarrow Cl_2(g) + 2e^-$$

5. a) The electron configurations for P (2.1), W (2.8.1), and R (2.8.8.1) all show one electron in their outermost shell. Elements with one valence electron belong to Group 1 of the periodic table. This group is generally known as the Alkali metals.

The general name given to the group in which P, W, and R belong is the $\boxed{\text{Alkali metals}}$.