Answer: Fentanyl is a polar molecule.
Explanation:
Oxygen being electro-negative will attract electron pairs towards itself and partial positive charge will generate on carbon atom in (C=O) bond.
Due to partial positive charge on carbon atom of (C=O) group will tend to attract electron pairs from its neighboring atoms by which lone pair on nitrogen atom will come in conjugation with (C=O) group which leaves partial positive charge on nitrogen atom.
Now partial positive charge is on the nitrogen atom which will further withdraws the electron density from the phenyl ring attached to it and positive charge will get de-localize at ortho and para positions in phenyl ring.
Hence, making the molecule of fentanyl polar.
