(a)(i) Ionic bond is the electrostatic force of attraction between oppositely charged ions/cations and anions.
OR
Ionic bond is defined as the type of bond that is formed from/ by/ through the transfer of electrons from one atom of an element (metal) to an atom of another (non - metal).
(ii) (I) – Ionic / electrovalent.
(II) – „Coordinate (Covalent) / dative.

(b) Oxidation number of sulphur in Na${}_2$S${}_2$O${}_2$;
2 x Na + 2 x S + 3 x 0 = 0
2 x 1 + 2s + 3(-2) = 0
2 + 2s – 6 = 0
2s = 4
s = +2

c) Farady's first law states that the mass of an element discharged during electrolysis is directly proportional to the of current passed.

(d)(i) NaHSO${}_4$, NaHCO${}_3$, KHSO${}_3$, etc. (ii) Mg(OH)Cl, Zn(OH)Cl, Zn(OH)NO${}_3$, etc.

e)(i) Sublimation energy. (ii) Electron affinity.

f) (i) Na${}_2$SO${}_{4(aq)}$ No effect on litmus paper/Neutral to litmus.
(ii) AlCl${}_{3(aq)}$ —Turns blue litmus paper red/Acidic to litmus.

(g) Efflorescence: Loss of (all apart from) water of crystallization by a substance on exposure to the air/Atmosphere.

(h) Activated Charcoal: (i) To remove colouring matter. (ii) To absorb gases. (iii) To remove impurities from liquids. (iv) Whitening of teeth. (v) To remove scent/To decolourize.

(i)(i) Hydrogenaton of Vegetable Oil: Production of margarine/Hardening of oils.
(ii) Cracking: Increase the yield of petrol/Improves the quality of petrol to produce raw materials or petrochemicals.
(iii) Esterification: Production of akanoates. —as solvents for paints/gums/cellulose. —in perfumery. —in making cellulose acetate (for photographic films). —as flavouring agents.
j) Ag${}^{-}$ + eg${}^{-}$ $\to$ Ag
96500c of electricity deposits I mole of Ag
10920c of electricity = $\frac{10920\times 1.0}{96500}$
= 0.113moles
= 0.11 moles.