The hydrogen atoms present in acetylene molecule are :

The hydrogen atoms in an acetylene (ethyne) molecule are acidic in nature. This characteristic is due to the sp hybridization of the carbon atoms in the triple bond [1]. In sp hybridization, the carbon atom has 50% s-character, which makes it more electronegative compared to sp2 or sp3 hybridized carbons. This high electronegativity causes the C-H bond to be more polarized, allowing the hydrogen atom to be released as a proton (H+) relatively easily. Consequently, acetylene can react with strong bases like sodium metal or sodamide (NaNH2) to form metal acetylides and liberate hydrogen gas. While acetylene is a very weak acid compared to carboxylic acids, it is significantly more acidic than other hydrocarbons like ethylene or ethane.

Sources

1. [1] https://www.t.soka.ac.jp/chem/iwanami/organic/ch06alkenes_v.pdf