What is meant by chirality of molecules ?

Explanation

**Step-by-Step Solution:**

1. **Definition of Chirality**: Chirality refers to the property of a molecule that makes it non-superimposable on its mirror image. This means that if you were to take a chiral molecule and place it in front of a mirror, the reflection you see cannot be aligned perfectly with the original molecule.

2. **Example of a Chiral Molecule**: Consider a carbon atom that is bonded to four different groups: a methyl group (CH3), an ethyl group (C2H5), a hydroxyl group (OH), and a hydrogen atom (H). This carbon atom is known as a chiral center or chiral carbon.

3. **Mirror Image**: When this chiral molecule is placed in front of a mirror, it creates a mirror image. If we rotate the original molecule by 180 degrees, the positions of the groups will change. For instance, the ethyl group (C2H5) that was above the plane of the molecule will now be below the plane after rotation.

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