Final answer:
NH3 (ammonia) is the strongest Brønsted base among the given options as it is more likely to accept a proton compared to H2O, and it is not an acid like HF and HCl.
Step-by-step explanation:
The question asks which of the following is a stronger Brønsted base: A. NH3 B. H2O C. HF D. HCl. To answer this, we need to understand what makes a good Brønsted base. In general, a Brønsted base is a species that can accept a proton (H+).
A strong Brønsted base is typically a molecule that does not hold onto its electrons very tightly, making it eager to accept a proton. Comparing the options given, NH3 (ammonia) is a stronger base than water (H2O), hydrofluoric acid (HF), and hydrochloric acid (HCl), which are not bases but acids. This assessment considers their abilities to accept protons as well as their relative acid strengths; NH3 has a higher inclination to accept a proton compared to H2O, and HF and HCl are stronger acids, thereby being very poor Brønsted bases.
Referencing the provided information and considering acidity constants, NH3 is the correct answer as it falls in the middle of those constants between H2O and CH4, indicating its moderate basic strength relative to the other options.