Question

terminal alkyne can be distinguished from the non-terminal alkyne and alkenes by using what?

Answer 1

Terminal alkynes are more acidic than other hydrocarbons due to the stability of the acetylide anion.
The sp hybrid orbital of the acetylide anion has more s character than sp² or sp³ orbitals and hence is closer to the nucleus. As a result the negative charge is stabilised the most in the alkynes.
Strong bases are required to deprotonate alkynes such as soda amide and potassium amide.

R-C≡C-H + NH₂^- → R-C​≡C^- + NH₃