Question

____ are compounds made up of only the elements carbon and hydrogen, where they have a double bond as a functional group.
options:

• carbohydrates
• alkenes
• alkanes
• alkyl halides

Explanation:

To solve this, we analyze each option:

• Carbohydrates contain C, H, O, so they're out.
• Alkanes have single C - C bonds, not double.
• Alkyl halides have halogen atoms (not just C and H).
• Alkenes are hydrocarbons (C and H only) with a carbon - carbon double bond as the functional group.

Answer:

C. Alkenes