The correct option is B CH3COOH and CH2=CH2
Alkaline potassium permanganate oxidises ethanol to ethanoic acid.
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Therefore, compound ‘A′ is ethanoic acid (CH3COOH).
Ethanol on heating with hot and conc. H2SO4 undergoes dehydration to give ethene (CH2=CH2), which is an unsaturated hydrocarbon and therefore, decolourises bromine water.
Therefore, compound ‘B′ is ethene (CH2=CH2).
Hence, the correct answer is option (b).