Which of the following statements correctly describes an $achiral$ molecule?

• A. It always rotates plane-polarized light.
• B. It contains at least one $chiral$ center.
• C. It cannot have a plane of symmetry.
• D. It is superimposable on its mirror image.

Answer: (D)

Verified step by step guidance

1. Understand the definition of a chiral molecule: A chiral molecule is one that is not superimposable on its mirror image, meaning it lacks an internal plane of symmetry.
2. Recognize that chirality often arises from the presence of at least one chiral center (usually a carbon atom bonded to four different groups), but this is not an absolute requirement for all chiral molecules.
3. Recall that chiral molecules typically rotate plane-polarized light, a property known as optical activity, but this is an observed behavior rather than a defining structural feature.
4. Note that a molecule with a plane of symmetry is achiral because it can be superimposed on its mirror image; thus, the absence of a plane of symmetry is a key characteristic of chirality.
5. Evaluate the statement 'It is superimposable on its mirror image' and recognize that this describes an achiral molecule, not a chiral one, so this statement is incorrect for describing chirality.