Answer:
1-Ethyl-3-methylidenecyclopentane
Step-by-step explanation:
Formula = C₈H₁₄. An alkane has formula C₈H₁₈. ∴ X contains 2 double bonds, 2 rings, or 1 ring and 1 double bond.
X absorbs only 1 mol of hydrogen. ∴ X contains 1 ring and 1 double bond.
Hydrogenation gives 1-ethyl-3-methylcyclopentane.
Ozonolysis gives formaldehyde, so X must contain a =CH₂ group.
Hydrogenation of X converted the =CH₂ to -CH₃.
X is 1-ethyl-3-methylidenecyclopentane.
You can see the reactions in the image below.