Due to sp-hybridization of carbon, the electrons of the C-H bond of ethyne are attracted towards carbon. As a result, carbon carries a partial negative charge while H carries a partial positive charge . Because of the presence of partial positive charge on H, ethyne forms H-bond with the F-atom of the HF molecule as shown :
`H-C-=overset(delta-)C-overset(delta+)H....... overset(delta-)F-overset(delta+)H`
