A collective noun is a noun that can be singular in form whilst referring to a group of people or things. Collective nouns are sometimes confused with mass nouns.ome collective nouns can stand alone, such as Britain has an army, but if the collective noun army is used to mean something other than an organized military force, you can say things like an army of women or an army of ants, and even an army of one.
Rainwater is slightly acidic because the CO2 in the atmosphere is soluble in water (the water in the air). When in solution CO2 forms a weak acid (Carbonic acid) which makes pure rainwater a weak acid. 1 person found this useful.
Acids in acid rain promote the dissolution of calcium carbonate by reacting with the carbonate anion. This produces a solution of bicarbonate. Because surface waters are in equilibrium with atmospheric carbon dioxide there is a constant concentration of carbonic acid, H 2 CO 3, in the water.hen water is in equilibrium with both CO 2 form the atmosphere and carbonate containing rock, the pH of the water is buffered to a pH of 8.3, close to the pKa of the weak acid bicarbonate HCO 3 - (pKa = 8.4). The buffered water resists changes to pH from additional acid or base.