(1) Give structure and IUPAC name of an optically active alkane having lowest molecular mass. Is there another alkane of the same molecular mass that is also optically active?
(2) Give example of a compound which exhibits both optical & geometrical isomerism.

Explanation

Such compound must contain an asymmetric carbon atom which will remain attached to a H - atom and three different alkyl groups (smaller size). So, optically active alkane having lowest molecular mass is 3 - methylexane `[CH_(3)CH_(2)overset(**)(C)H(CH_(3))CH_(2)CH_(2)CH_(3)]`. Another optically active alkane with the same molecular mass is 2,3 - dimethylpentane `[CH_(3)CH_(2)overset(**)(C)H(CH_(3))_(2)]` which is a chain isomer of the first one.
(2) Pent - 3 - en - 2 - ol `[CH_(3)overset(**)(C)H(OH)CH=CHCH_(3)]` exhibits both geometrical and optical isomerism because the compound contains as asymmetric carbon atom and each of the doubly bonded carbon atoms is attached to two different groups.