Final answer:
The ability to dissolve carbon dioxide CO₂ and form ionic compounds like CaCO₃ allows oceans to store carbon and create a significant carbon reservoir.
Step-by-step explanation:
The property of water that allows the oceans to store carbon dioxide is its ability to dissolve CO₂ and react with other compounds to form ionic compounds. Specifically, dissolved carbon dioxide (CO₂) from the atmosphere reacts with water molecules to produce carbonic acid, which then undergoes further ionization to bicarbonate and carbonate ions.
Some of this, in the presence of calcium ions in seawater, forms calcium carbonate (CaCO₃), contributing to the shells of marine organisms. As these organisms die, their shells create sediments that may eventually become limestone, forming a significant carbon reservoir.