Q.Which of the following is optically active?

Step 1. For a molecule to be optically active (in the simplest sense tested here), it needs at least one carbon bonded to four DIFFERENT groups (a stereocentre).

Step 2. In 2-methylpentane, CH3-CH(CH3)-CH2-CH2-CH3, the branching carbon (C2) is bonded to: a methyl (C1), a second methyl (the branch), a propyl chain (C3-C4-C5), and an H -- but the two methyls are IDENTICAL, so C2 is not a stereocentre; no other carbon in the molecule has four different groups either. …

For each candidate structure, identify the carbon most likely to be a stereocentre and list its four attached groups explicitly; if any two of the four are identical, that carbo …

• Assuming any molecule with an -OH or a branched chain must be chiral -- chirality specifically requires FOUR DIFFERENT groups on one carbon, not just the presence of a functional group or a branch. …