Question

The minimum number of carbon atom required for an alkane to exhibit optical activity is:

• A. 5
• B. 6
• C. 7
• D. 8

Answer 1

The correct option is C 7

For exhibiting optical activity compound should lack any elements of symmetry. Genrally, compounds having chiral carbon lacks the elements of symmetry. These chiral compounds will give non-superimposable mirror image which rotate light in clockwise and anti-clockwise direction to exhibit optical acitivity.
Chiral compound have asymmetric carbon centre, it means, the carbon will attach to four different groups.
Here, only with carbon atom we should make a optivally active compound.
So lets take the centre carbon and it substituted to one hydrogen and three different carbon group which are $C{H}_3,C_2{H}_5,C_3{H}_7$.
Therefore, minimum number of carbon atom for an alkane required to exhibit optical activity is 7.