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.
This precipitation could include snow, fog or bits of dry material in the atmosphere which drift down to Earth. Acid rain is formed when chemicals such as sulfur dioxide (SO2) or nitrogen oxides (NOx) react with water in the atmosphere to form mild solutions of sulfuric or nitric acid. The acidity of solutions is measured on a logarithmic pH scale from 0 to 14 with 0 being most acidic and 14 being most alkaline and 7 as neutral.