Which of the following molecules is chiral?

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

Answer: (D)

Verified step by step guidance

1. Identify the concept of chirality: A molecule is chiral if it has a carbon atom bonded to four different substituents, making it a stereocenter (chiral center).
2. Examine each given molecule and look for any carbon atom that is attached to four different groups. For example, in \( \mathrm{CH_3CH_2OH} \) (ethanol), check if any carbon has four distinct substituents.
3. For \( \mathrm{CH_3CH_2CH_3} \) (propane), note that all carbons are bonded to hydrogens and carbons in a symmetrical way, so no chiral center exists.
4. For \( \mathrm{CH_3CH_2Cl} \) (chloroethane), check if any carbon has four different groups; typically, the carbons are bonded to hydrogens and one chlorine, but not four distinct groups.
5. For \( \mathrm{CH_3CHBrClF} \), focus on the carbon bonded to Br, Cl, F, and CH3 groups. Since this carbon is attached to four different substituents, it is a chiral center, making the molecule chiral.