Given the equation representing a reversible reaction:NH3(g) + H2O(l) <=> NH4+(aq) + OH-(aq)According to one acid-base theory, the reactant that donates an H+ ion in the forward reaction is(1) NH3(g) (2) H2O(l)(3) NH4+(aq) (4) OH-(aq)
The answer is (2).
The acid-base theory in question here is the Bronsted-Lowry theory, according to which an acid is any substance that donates a H+ ion. In this reaction, it is H2O that donates an H+ ion to NH3.