Which of the following carboxylic acids, when its vapours are passed over heated MnO at 300^ C , yields propanone as the major product?

Step-by-step solution

When the vapours of a carboxylic acid are passed over heated MnO at 300^ C , catalytic decomposition occurs to form a symmetrical ketone. The general reaction is: 2 RCOOH MnO , 300^ C R-CO-R + CO ₂ + H ₂ O To obtain propanone ( CH ₃ COCH ₃ ), the alkyl group R must be a methyl group ( CH ₃ ). Thus, the required carboxylic acid is ethanoic acid ( CH ₃ COOH ). Answer: Ethanoic acid