Answer is: oxidation number of boron in boric acid is +3.
Boric acid (H₃BO₃) has neutral charge.
Hydrogen (H) has oxidation number +1.
Oxygen (O) has oxidation number -2.
Calculate oxidation number of boron (B):
3 · (+1) + x + 3 · (-2) = 0.
x = -3 + 6.
x = +3; oxidation number of boron.
The oxidation number of an atom is the charge that atom would have if the compound was composed of ions.
