Which of the following molecules is chiral?

• A. ${\mathrm{CH}}_3\mathrm{COOH}$
• B. ${\mathrm{CH}}_3\mathrm{CHBrClF}$
• C. ${\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{Cl}$
• D. ${\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{OH}$

Answer: (B)

Verified step by step guidance

1. Identify the concept of chirality: A molecule is chiral if it has at least one carbon atom bonded to four different substituents, making it a stereocenter (chiral center).
2. Examine each molecule's structure to find any carbon atoms attached to four distinct groups.
3. For the molecule \( \mathrm{CH_3COOH} \) (acetic acid), note that the central carbon is bonded to two oxygen atoms (one double bonded, one single bonded), a hydroxyl group, and a methyl group, but it does not have four different substituents because of the two oxygens; thus, it is achiral.
4. For the molecule \( \mathrm{CH_3CHBrClF} \), focus on the second carbon which is bonded to a hydrogen, bromine, chlorine, and fluorine—four different substituents—making this carbon a chiral center and the molecule chiral.
5. For the molecules \( \mathrm{CH_3CH_2Cl} \) and \( \mathrm{CH_3CH_2OH} \), the carbons do not have four different substituents; the second carbon is bonded to two hydrogens and one other group, so these molecules are achiral.