Answer: [tex]HCl(g)[/tex] is acting as a Bronsted acid.
Explanation:
According to the Bronsted-Lowry conjugate acid-base theory, an acid is defined as a substance which donates protons and thus forming conjugate base and a base is defined as a substance which accepts protons and thus forming conjugate acid.
For the given chemical equation:
[tex]HCl(g)+NH_3(aq)\rightarrow NH_4^+(aq)+Cl^-(aq)[/tex]
Here, [tex]HCl[/tex] is loosing a proton, thus it is considered as a bronsted acid and after losing a proton, it forms [tex]Cl^-[/tex] which is a conjugate base.
And, [tex]NH_3[/tex] is gaining a proton, thus it is considered as a bronsted base and after gaining a proton, it forms [tex]NH_4^+[/tex] which is a conjugate acid.
