identify whether each compound is a straight chain, branched chain, or cycloalkane.

Explanation:

Step1: Analyze first compound

The first compound has a carbon - chain with a methyl group ($-CH_3$) attached to a central carbon in the main chain, so it is a branched - chain.

Step2: Analyze second compound

The second compound has a ring structure with carbon atoms and functional groups attached to the ring, so it is a cycloalkane.

Step3: Analyze third compound

The third compound has a continuous, unbranched carbon - chain with a double bond, so it is a straight - chain.

Answer:

Branched chain, Cycloalkane, Straight chain