The total number of structural isomers of molecular formula C6H14 is :A 4 B 5 C 6 D 7

The molecular formula C6H14 represents an alkane with 6 carbon atoms. The structural isomers of this alkane can be determined by changing the arrangement of the carbon atoms.

1. Hexane: All six carbon atoms are arranged in a straight chain.
2. 2-Methylpentane: Five carbon atoms are arranged in a straight chain, with the sixth carbon atom attached to the second carbon atom in the chain.
3. 3-Methylpentane: Five carbon atoms are arranged in a straight chain, with the sixth carbon atom attached to the third carbon atom in the chain.
4. 2,2-Dimethylbutane: Four carbon atoms are arranged in a straight chain, with two additional carbon atoms each attached to the second carbon atom in the chain.
5. 2,3-Dimethylbutane: Four carbon atoms are arranged in a straight chain, with one additional carbon atom attached to the second carbon atom in the chain and another one attached to the third carbon atom in the chain.

So, the total number of structural isomers of molecular formula C6H14 is 5. Therefore, the correct answer is B. 5.