Concept:Metamerism requires a polyvalent (multivalent) functional group flanked by alkyl chains on at least two sides so that the alkyl groups can be varied.
Solution:- Ethers (\( \text{R--O--R'} \)), Secondary amines (\( \text{R--NH--R'} \)), and Ketones (\( \text{R--CO--R'} \)) all have a central functional group bonded to two alkyl groups. Changing the length of these alkyl groups creates metamers.
- Aldehydes (\( \text{R--CHO} \)) have the carbonyl group at the terminal end of the chain. It is monovalent (attached to only one R group and one fixed Hydrogen).
- Because the aldehyde group can only exist at the end of a chain, it cannot shift between different alkyl groups, making metamerism impossible.
Why other options are incorrect:Options A, B, and C possess polyvalent functional groups that allow for unequal distribution of carbon atoms on either side, hence they do show metamerism.
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