Which of the following are enantiomers
**Core Concept**
Enantiomers are pairs of molecules that are mirror images of each other but are not superimposable. This property is known as chirality, and it arises due to the presence of a stereocenter (a carbon atom bonded to four different groups) in the molecule. Enantiomers have the same physical and chemical properties, except for their ability to rotate plane-polarized light in opposite directions.
**Why the Correct Answer is Right**
Enantiomers are molecules that are non-superimposable mirror images of each other. This property is essential in pharmacology, as it can affect the efficacy and toxicity of a drug. For example, the enantiomers of a drug like thalidomide have different effects on the body - one enantiomer is a sedative, while the other is a teratogen. The correct answer will be a pair of molecules that have this non-superimposable mirror image property.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not describe a pair of molecules that are mirror images of each other.
* **Option B:** This option is incorrect because it does not have a stereocenter, which is necessary for chirality.
* **Option C:** This option is incorrect because it does not describe a pair of molecules that have the same physical and chemical properties.
**Clinical Pearl / High-Yield Fact**
When dealing with enantiomers, it's essential to remember that small changes in molecular structure can have significant effects on a drug's efficacy and toxicity. This is why enantiomer-specific drugs are often developed to target specific pathways or receptors.
**Correct Answer:** C. Methylphenidate and its R-enantiomer.