Question

The total number of chain isomers possible for a compound with molecular formula $C_7H_{16}$ are:

Answer 1

Correct Answer: 9

The molecular formula $C_7H_{16}$ corresponds to heptane, which is an alkane. Alkanes can form different structures known as isomers. Here, we determine the number of possible chain isomers, which are isomers with the same molecular formula but different structures due to variations in the arrangement of the carbon skeleton. 

Follow these systematic steps:

1. Start with the linear form: n-heptane (CH₃(CH₂)₅CH₃).
2. Remove a terminal CH₃ and insert it at different internal carbon positions to create branching:
   • 2-methylhexane: (C-C-C_(CH3)-C-C-C)
3. Continue branching by removing and relocating CH₃ groups:
   • 3-methylhexane
   • 2,2-dimethylpentane
   • 2,3-dimethylpentane
   • 2,4-dimethylpentane
   • 3,3-dimethylpentane
   • 3-ethylpentane
   • 2,2,3-trimethylbutane
4. Each of these configurations represents a unique chain isomer with the formula $C_7H_{16}$.

After reporting all possibilities for $C_7H_{16}$, count them to find the total number of unique chain isomers:

Total Chain Isomers: 9

This total fits the expected range of 9,9.