IUPAC name of the alkene which contains three C-C, eight C – H bonds and one C – C bond and gives two moles of an aldehyde of molar mass 44u on ozonolysis is

 Acetaldehyde is the aldehyde having a molar mass of 44 u. On ozonolysis, 2 molecules of acetaldehyde are produced. 

Therefore, but-2-ene contains three $\mathrm{C}-\mathrm{C}$, eight $\mathrm{C}-\mathrm{H\sigma }$ bonds are one $\mathrm{C}$ $\mathrm{C\pi }$ bond.