Final answer:
The benzylic carbons are the carbon atoms directly attached to the benzene ring in each structure.
Step-by-step explanation:
The benzylic carbons are the carbon atoms directly attached to the benzene ring.
For the given structures:
a. 3-ethyl-4-methyl-3-heptene: The benzylic carbon is the carbon attached to the ethyl group, which is at position 3 of the carbon chain.
b. 3,3-diethyl-1-pentyne: The benzylic carbons are the two carbon atoms directly attached to the ethyl groups at positions 3 and 3 of the carbon chain.
The complete question is: Identify the benzylic carbons in each of the structures. Place an asterisk "*" next to each benzylic carbon in each structure.