Isomerism

To determine which compound exhibits metamerism, we need to understand the concept of metamerism in organic chemistry. Metamerism is a type of isomerism where compounds (metamers) have the same molecular formula but differ in the alkyl groups attached to a functional group or the same multivalent atom.

Let's analyze each of the given options:

1. : This is the molecular formula for alkanes such as pentane. Alkanes do not exhibit metamerism as there is no functional group or heteroatom for chain variation.
2. : This is the molecular formula for alcohols like propanol and ethers such as methoxyethane. However, with only three carbons, there isn't enough variability in chain structure to exhibit metamerism.
3. : This corresponds to aldehydes and ketones, like propanal and acetone, but again, similar to the previous case, there are not enough distinct chains to exhibit metamerism with this small number of total carbons.
4. : This formula can correspond to ethers like diethyl ether (CH₃CH₂OCH₂CH₃) and methyl propyl ether (CH₃OCH₂CH₂CH₃). These represent structural isomers with different alkyl groups on either side of the oxygen atom, thus displaying metamerism.

Thus, the correct answer is , as it can form metamers with different alkyl group arrangements around the ether functional group.