Question

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

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

Answer 1

The correct option is A 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. Compound No. of C atoms No. of H atoms

hept-1-ene	7	14
hex-1-ene	6	12
pent-1-ene	5	10
but-1-ene	4	8

The alkene with fourteen hydrogen atoms (same as oct-1-yne) is hept-1-ene.