When 2,4-hexadiene is protonated, a resonance-stabilized secondary allylic carbocation is formed. Draw the curved arrow notation below that shows the movement of electrons between the two major resonance structures.

see the image for the structure of the allylic carbocation

Explanation:

When 2,4-hexanediene is protonated at the 5-position as shown in the image, a carbonation is formed which can be stabilized by resonance. The positive charge can be found on carbon 4 or carbon 2 due to resonance of the allylic carbonation. The both structures are shown and electron movements were depicted using curved arrow notation in the structures shown in the image attached.

1 a

2 d

3 a

4 c

explanation: