Concept:The image shows an amide linkage,
−CONH−, which is the characteristic bond of polyamides (nylons).
Explanation:Nylon 6, Nylon 6,6, and Nylon 2,6 are all polyamides, so each contains the
−CONH− amide linkage in its polymer chain.
PAN (polyacrylonitrile) is a vinyl polymer with the repeating unit
[−CH2​−CH(CN)−]n​.
It contains nitrile groups,
−C≡N, and has no amide linkage.
Therefore, PAN is the polymer that does not contain the group shown in the image.
Answer:Option A: PAN
