Question

Oct-1-yne has the same number of hydrogen atoms as of __________.

• A. hex-1-ene
• B. pent-1-ene
• C. hept-1-ene
• D. but-1-ene

Answer 1

The correct option is C hept-1-ene

Oct-1-yne has eight carbon atoms and fourteen hydrogen (H) atoms as shown.

General formula for alkenes is${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$.
$\therefore$ For an alkene with fourteen H atoms:
2n = 14 $\Rightarrow \text{n}=7$

So, the alkene should have seven carbon atoms and fourteen hydrogen atoms.
$$\begin{array}{ccc}Compound& No.ofCatoms& No.ofHatoms\\ hept-1-ene& 7& 14\\ hex-1-ene& 6& 12\\ pent-1-ene& 5& 10\\ but-1-ene& 4& 8\end{array}$$
The alkene with fourteen hydrogen atoms (same as oct-1-yne) is hept-1-ene.