why is hydrogen bonding inly possible with hydrogen?

Answer 1

It's the arrangement of the O-H bond. The oxygen is quite electronegative and pulls the electrons shared between O and H toward it, making it more negative and making the H partially positive. So the O atoms are attracted to the H atoms of other molecules (those attached to O). H bonding also occurs from other electronegative atoms; namely, N and F. Atoms with lower electronegativities (all other atoms except N, F, O) are too low to show this property.