Question

A certain hydrocarbon has a molecular formula of C9H16. Which of the following is not a structural possibility for this hydrocarbon? Select all that apply. a)It contains one ring and one double bond. b) It is an alkyne. c) It contains two double bonds and no rings. d) It is a cycloalkane.

Answer 1

Answer: Option (d) is the correct answer.

Explanation:

It is given that molecular formula is $C_{9}H_{16}$. Now, we will calculate the degree of unsaturation as follows.

Degree of unsaturation = $C_{n} - \frac{\text{monovalent}}{2} + \frac{\text{trivalent}}{2} + 1$

                                  = $9 - \frac{16}{2} + 1$

                                  = 9 - 8 + 1

                                  = 2

As the degree of unsaturation comes out to be 2. It means that this compound will contain one ring and one double bond.

Yes, this compound could be an alkyne as for alkyne D.B.E = 2.

But this compound cannot be a cycloalkane because for a cycloalkane D.B.E = 1 which is due to the ring only.

Thus, we can conclude that it is a cycloalkane is not a structural possibility for this hydrocarbon.