Which of these equations correctly expresses the self-ionization of water? Upper H subscript 2 upper O superscript plus upper H subscript 3 upper O superscript plus double-headed arrow upper H subscript 2 upper O plus upper O upper H superscript minus. Upper H subscript 2 upper O plus upper H subscript 2 upper O double-headed arrow 2 upper O upper H superscript minus. Upper H subscript 2 upper o plus upper H subscript 2 upper O double headed arrow 2 upper H subscript 3 upper O superscript plus. Upper H subscript 2 upper O plus upper H subscript 2 upper O double-headed arrow upper H subscript 3 upper O superscript plus, plus upper O upper H superscript minus.