A chiral molecule is one that is not superimposable on its mirror image, lacking a plane of symmetry. It must have a chiral center, typically a carbon atom with four different substituents.

Option 1: Cyclohexane derivative. Likely symmetric, not chiral.

Option 2: Molecule with a chiral center (carbon with H, CH₃, Cl, and a different group). This is chiral.

Option 3: Symmetric alkene. No chiral center, not chiral.

Option 4: Linear molecule. Likely symmetric, not chiral.

Final Answer: The second molecule is chiral.