Final answer:
A ketone cannot have only two carbon atoms because its structure necessitates the carbonyl group being bonded to two carbon groups, making three carbon atoms the minimum for a ketone. Saturated fatty acids only have single bonds between carbon atoms, while unsaturated fatty acids contain double or triple bonds. The correct answer is:
b) Steric hindrance
Step-by-step explanation:
Why It Is Not Possible to Prepare a Ketone with Only Two Carbon Atoms
The structure of a ketone requires that the carbonyl group (C=O) be bonded to two additional carbon atoms. Therefore, it is not possible to have a ketone with only two carbon atoms because there must be at least three carbon atoms present for it to qualify as a ketone. The smallest ketone is acetone, which has three carbon atoms and is also commonly known by its IUPAC name propanone.
Differences and Similarities Between Saturated and Unsaturated Fatty Acids
Both saturated and unsaturated fatty acids have the -COOH (carboxyl) group in common, which is characteristic of carboxylic acids. A saturated fatty acid has a hydrocarbon chain with only single bonds between carbon atoms, making it 'saturated' with hydrogen atoms. In contrast, an unsaturated fatty acid contains one or more double or triple bonds within the hydrocarbon chain, indicating the presence of fewer hydrogen atoms.