Question

Why is penta-2,3-diene optically active?

Answer 1

First draw its structure and identify the stereocentres.
If it exists and has plane os symetry then it would not called as optical isomer.
And this molecule is symmetrical about the central Carbon atom.
The no. os sterocentres are 2.
Hence for the even no. of stereocentres, No. of optical active isomers = > 2^(n-1) => 2^1 = 2.

Answer 2

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Yes 2,3-pentadiene shows the optical activity.as there are 2 cumulated double bonds the terminal carbons are mutually perpendicular to each other & they have the same groups attached to them i.e CH3& H on each terminal carbon.so the molecule becomes chiral as plane passing through it does not cut it in symmetrical manner.