Question

If lengths of four samples of a compound are in order D>B>A>C ($\theta ,c$ are same), the order of specific rotations is:

• A. A
• B. B
• C. C
• D. D

Answer 1

Specific rotation of a sample containing an optically active compound is inverserly proportional to its length assuming that the other conditions remain the same.
Hence, the order of the specific rotations must be the reverse of the order of the lengths of samples.
Therefore C>A>B>D is the required order.