Stereoisomerism from chiral centers or geometric isomerism

Steps:

• Identify types of stereoisomerism: optical (chiral centers) or geometric (restricted rotation around double bonds).
• Examine each compound for a chiral carbon (four different substituents) or double bond with non-identical groups on each carbon.
• For A and D, check alkene geometry; for B, check carbon substituents; for C, check tetrahedral carbon.
• Select the compound with a qualifying feature.

Why B is correct:

• 2-Chloropropan-1-ol (CH₃CH(Cl)CH₂OH) has a chiral center at C2 with four different groups (CH₃, Cl, H, CH₂OH), allowing optical isomers per chirality definition.

Why the others are wrong:

• A: 2-Methylbut-2-ene has a double bond where one carbon bears two identical methyl groups, preventing cis-trans isomerism.
• C: Difluorobromomethane (CHBrF₂) has two identical F atoms on the central carbon, so no chirality.
• D: Pent-1-ene is a terminal alkene with two H atoms on C1, allowing no geometric isomerism and no chiral center.

Final answer: B