Answer:
HF is the acid
Explanation:
The Brønsted-Lowry theory defines the acids and bases in chemistry as follows:
An acid is the species that can donate a proton
A base can accept protons.
In the reaction:
HF(aq) + NH₃(aq) → NH₄⁺(aq) + F⁻(aq)
As you can see, HF can donate its proton to produce F⁻: HF is the acid
In the same way, NH₃ is accepting a proton, NH₃ is the base.
