(i) Structural formula of benzene (C₆H₆):
Benzene has a ring of 6 carbon atoms with alternating double bonds:
$$\text{Hexagonal ring with alternating single and double bonds between carbon atoms, each C bonded to one H}$$
(A regular hexagon with alternating double bonds, each carbon bonded to one H atom.)
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(ii) Carbon has 4 electrons in its outermost shell. To form C⁴⁺, it would need to lose 4 electrons, requiring a very large amount of energy. To form C⁴⁻, it would gain 4 electrons, which would be difficult to hold in the nucleus with only 6 protons. Both processes are energetically unfavourable, so carbon forms covalent bonds instead.
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(iii) The bond formed between carbon and hydrogen is a covalent bond (non-polar covalent bond), formed by equal sharing of electrons.
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(iv) Ethanol is converted to ethanoic acid by oxidation, using an oxidising agent such as alkaline KMnO₄ or acidified K₂Cr₂O₇.
$$\text{CH}_3\text{CH}_2\text{OH} \xrightarrow{[\text{O}]} \text{CH}_3\text{COOH}$$
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(v)
$$\text{CH}_3\text{COOC}_2\text{H}_5 + \text{NaOH} \longrightarrow \text{CH}_3\text{COONa} + \text{C}_2\text{H}_5\text{OH}$$
(Sodium ethanoate + Ethanol)
Source: Carbon and its Compounds, Chapter 4, Sections 4.2.2, 4.4
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