Question

The total number of structural isomers of $C_{5}H_{11}F$ is:

• A. 6
• B. 8
• C. 10
• D. 9

Hint:

To find isomers, first draw all possible carbon chains (Pentane, Isopentane, Neopentane), then place the functional group on every unique carbon.

Answer 1

The Correct Option is B

Step 1: Concept
Structural isomers are molecules with the same molecular formula but different bonding arrangements. For $C_{5}H_{11}F$, we consider the different carbon skeletons and the position of the Fluorine atom.

Step 2: Pentane Skeleton (3 isomers)
1-fluoropentane, 2-fluoropentane, and 3-fluoropentane.

Step 3: Isopentane Skeleton (4 isomers)
1-fluoro-2-methylbutane, 2-fluoro-2-methylbutane, 3-fluoro-2-methylbutane, and 4-fluoro-2-methylbutane (also called 1-fluoro-3-methylbutane).

Step 4: Neopentane Skeleton (1 isomer)
1-fluoro-2,2-dimethylpropane. Summing these up: $3 + 4 + 1 = 8$ structural isomers. Final Answer: (B)