Question

Which substance is acting as the Brønsted-Lowry acid in the following chemical reaction? NH4 + OH- yields NH3 + H2O

Answer 1

The answer to this question is A. NH4+. Its conjugate base is NH3 so NH4 donates a proton to OH- to become NH3 in the equilibrium reaction.

Answer 2

The  the Brønsted-Lowry acid donates H⁻.
In this reaction Particle that  loose H⁺ is A. NH4⁺ ion.