A. (i) Electron affinity [1mark]
(ii) Ionisation [1 mark]
B. (i) Sodium sulphate is prepared by the neutralisation of sodium carbonate and sulphuric acid. [1 mark]
(ii) Zinc sulphate is prepared by the displacement reaction between zinc and sulphuric acid. [1 mark]
C. (i) Ionic compounds have high melting points because there is a strong electrostatic force of attraction between the oppositely charged ions and hence a large amount of energy is required to break the strong bonding force between ions. [1 mark]
(ii) On the periodic table, ionisation energy generally increases as you move left to right across a period. This is due to increasing nuclear charge, which results in the outermost electron being more strongly bound to the nucleus.
(iii) Acetic acid is weak electrolyte which dissociates partially whereas HCl is strong electrolyte which dissociates completely. Therefore, conductivity of dilute hydrochloric acid is greater than acetic acid.
D. (i) When we go down the group in the periodic table, the electron shells are added to the elements. We can also say that, in successive periods, the electron shell number increases by one. Hence the order of elements according to the increase in number of electron shells is as follows, He < Ne < Ar.
(ii) The reactivity series of metals, also known as the activity series, refers to the arrangement of metals in the descending order of their reactivities.
So, the correct order is: Pb < Zn < Ca < K.
(iii) We know that atomic size increases from right to left and from top to bottom in the Periodic Table. So the correct order of atomic radius is Li < Na < K.