(a)(i) Esterification is the reaction between alkanols and alkanoic acids to form alkanoates in the presence of mineral acids
(ii) Saponification is the reaction between caustic soda/sodium hydroxide/alkalis and fats or oils to produce salts or fatty acids/soap.

(b)(i) The general molecular formula of alkynes is C\(_n\)H\(_{2n-2}\)
(ii) The molecular formula of ethylethanoate is C\(_4\)H\(_8\)O\(_2\) and its empirical formula is C\(_2\)H\(_4\)O.
(iii) The structure of 1, 1, 2, 2 - tetrabromoethane is

2C\(_2\)H\(_5\)OH + 2Na \(\to\) 2C\(_2\)H\(_5\)ONa + H\(_2\)

(c)(i) Stage (i) is fractional distillation;
Stage (ii) is cracking;
Stage (iii) is chlorination or alogenation or addition:
Stage (iv) is polymerisation
(ii) X is ethene / C\(_2\)H\(_4\). Y is chlorine / CI
(iii) IUPAC name of the structure below is 1, 2, dichlorethane

(iv) The reaction conditions for the polymerisation of ethene (stage iv) are high temperature (150°C to 300°C). High pressure (any pressure 500 to 1500 atmosphere) presence of a trace of oxygen or peroxides.

(d)(i) Palm wine Froths or foams because of the process of fermentation. The CO\(_2\) bubbles produced, cause the mixture to foam.
(ii) Palm wine tastes sour after some days because it has been oxidized to ethanoic by bacteria Atmospheric oxygen i.e aerial oxidation.