Which of the following species in a lake/pond is not a proton accepter?

Correct option is A

The correct answer is (a) Al3+. The aluminum ion (Al3+) is a Lewis acid, meaning it tends to accept electrons rather than protons. It acts as a proton donor by hydrolyzing in water to form acidic solutions. In contrast, the other species can accept protons (i.e., they can act as bases):
· Natural Organic Matter: Contains functional groups like carboxylate (−COO−) that can accept protons.
· HS−: A conjugate base of hydrogen sulfide (H₂S), which can accept a proton to form H₂S.
· H3SiO4−​: A species that can accept a proton to form H4SiO4.
Information Booster: 1. Proton Accepters (Bases): Substances that can accept protons (H+).
2. Al3+\text{Al}^{3+}Al3+: A Lewis acid that tends to hydrolyze in water, forming acidic species like Al(OH)2+.
3. Natural Organic Matter: Often contains acidic and basic functional groups that interact with protons.
4. HS−: A base that can accept protons, forming hydrogen sulfide (H₂S).
5. H3SiO4−​: A silicate ion that can act as a base by accepting protons.