Chirality in Molecules
Chirality in molecules refers to the property of a molecule that is not superimposable on its mirror image. This property arises when a molecule contains an asymmetric carbon atom, also known as a chiral center.

Chiral and Achiral Molecules
Chiral molecules are those that have a chiral center and exist in two non-superimposable mirror image forms known as enantiomers. Achiral molecules, on the other hand, do not possess a chiral center and are superimposable on their mirror images.

Analysis of Molecules

H2O
- Water (H2O) is an achiral molecule.
- It does not have a chiral center, and its mirror image is superimposable on the original molecule.
- Therefore, water is an example of an achiral molecule.

CH2BrCl
- CH2BrCl is a chiral molecule.
- It contains an asymmetric carbon atom, which gives rise to chirality.
- The presence of different substituents (hydrogen, bromine, and chlorine) attached to the asymmetric carbon results in non-superimposable mirror images.
- Hence, CH2BrCl is a chiral molecule.

CHBrClF
- CHBrClF is an achiral molecule.
- Although it contains an asymmetric carbon atom, the presence of two identical substituents (chlorine and bromine) cancels out the chirality.
- The mirror image of CHBrClF is superimposable on the original molecule due to the symmetry created by the two identical substituents.
- Therefore, CHBrClF is an example of an achiral molecule.
In conclusion, H2O and CHBrClF are achiral molecules, while CH2BrCl is a chiral molecule due to the presence of an asymmetric carbon atom.