Final answer:
In Bronsted-Lowry theory, NH4+ acts as an acid, Cl- is a very weak base, H2O can be either an acid or base, and O2 is neither typically considered an acid nor a base.
Step-by-step explanation:
To identify whether the species NH₄⁺, Cl⁻, H₂O, and O₂ act as Bronsted-Lowry acids or bases, we look at their ability to donate or accept protons. According to Bronsted-Lowry theory, an acid is a proton donor, whereas a base is a proton acceptor.
- NH₄⁺ - Ammonium ion is a proton donor, so it is a Bronsted-Lowry acid.
- Cl⁻ - Chloride ion is typically the conjugate base of HCl, but it is a very weak Bronsted-Lowry base as it can very seldomly accept a proton.
- H₂O - Water can act as both an acid and a base; it can donate a proton (acid) or accept a proton (base), depending on the reaction.
- O₂ - Oxygen gas is not typically considered a Bronsted-Lowry acid or base as it does not readily donate or accept protons in its diatomic form.