Question

Why are OH, NH, and FH bonds so polar?

Answer 1

The reason these bonds are so polar is due to the electronegativity difference between the two atoms. Electronegativity defines an atom's affinity to attract electrons. When an atom with a high electronegativity (O,N,or F) is bonded with an atom with a small electronegativity, the electron cloud will be pulled towards the more electronegative species creating a dipole (the H carries a partial positive charge from it's lack of electrons and the O carries a partial negative charge).

This link shows a periodic table with the electronegativity of each atom where you can see that O,N, and F are some of the most electronegative atoms that exist.
http://www.tutor-homework.com/Chemistry_Help/electronegativity_table/electronegativity.html

Answer 2

partial positive charge develop on H atom due to the strong pull on the electron cloud by the highly electronegative atoms,{in order;F,O and N},around,which in turn gain partial negative charges,to make the entire molecule polar,strong enough even to change the physical state. refresh-water- polarity;liquid Ammonia&Freons

Answer 3

because they can form hydrogen bond with polar solvents.