I think the correct answer would be strong gravity. The factor that allows the earth to hold onto water would be the strong gravitational pull of the earth. In fact, it is what holds everything onto earth not only water. Hope this answers the question.
Answer:
The carbon dioxide reacts with water to form carbonic acid.
Explanation:
CO2+H2O=H2CO3
In this reaction carbon dioxide(CO2) and water(H2O) act as reactant to form carbonic acid(H2CO3) which is a weak acid.
The above reaction is an important reaction carried out by bicarbonate buffer system to maintain normal acid base balance inside our body but this buffer system includes an additional reaction in with carbonic acid is ionized to form H+ and HCO3- ion or bicarbonate ion.
