Question

Which of the following is 'not' true about enantiomers?

• A. They have the same chemical reactivity.
• B. They have the same specific rotation.
• C. They have the same melting or boiling point.
• D. They have the same refractive index.

Hint:

Enantiomers are non-superimposable mirror images.

Answer 1

The Correct Option is B

Step 1: Recall what enantiomers are.
Enantiomers are two molecules that are non-superimposable mirror images of each other (like left and right hands).

Step 2: List the properties they share.
In an ordinary (achiral) environment enantiomers have identical physical properties such as melting point, boiling point, density, refractive index and solubility, and identical chemical reactivity toward achiral reagents.

Step 3: Find the one property that differs.
The single property that is different is how they rotate plane-polarised light. They rotate it by the same magnitude but in opposite directions (one is +, the other is -).

Step 4: Apply this to the statement.
The claim that they have the same specific rotation is wrong, because their specific rotations are equal in size but opposite in sign.

Step 5: Conclude.
So the statement that is NOT true is that they have the same specific rotation.

\[ \boxed{\text{They have the same specific rotation.}} \]