When it acts as a base, which atom in hydroxylamine accepts a proton?

The oxygen atom accepts the proton. The oxidation number of O is -2, meaning that there are two unshared electrons in the valence shell; In the ClO- ion, one of these is shared with the Cl- ion, leaving an unshared electron on the oxygen atom, which is what the hydrogen atom shares its electron with, becoming the proton accepted by the O atom.

Iwould you figure it out but you don't have a picture or in your question as to what the physical property you're looking for is