What conditions need to be present for an atom to form hydrogen bonds?

The 2 conditions given for hydrogen bonding are:

1) A hydrogen atom must be covalently bonded to O, N or F atom. I can understand this part, as O, N and F are highly electronegative and will leave the H with a positive dipole (more or less a H+ ion).

2) The other condition is that the atom with a lone pair which the H is hydrogen-bonded to must be O, N or F.

HOPE THIS HELPS

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ITZ RASPUTIN020

the answer is sex-linked recessive.