9. According to an "alternative theory", H2O is

considered to be a base when it

(1) donates an electron. (3) donates a proton

(2) accepts an electron (4) accepts a proton

Respuesta :

Answer:(4) ----accepts  a proton

Explanation:

H2O water can produce both hydrogen and   hydroxide ions

H2O --> H+ + OH-

According to the Bronsted-Lowry theory, it can be a proton donor and a proton acceptor.this means that It can donate a hydrogen ion to become its conjugate base, or  can accept a hydrogen ion to form its conjugate acid,

When , a water molecule, H2O accepts a proton it will act as a Brønsted-Lowry base especially when dissolved in a strong acidic medium. for eg

HCl + H2O(l) → H3O+(aq) + Cl−(aq)

Here, Hydrochloric acid is a strong acid and ionizes completely in  water, since it is more acidic than water, the water will act as a base.