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.
Acidity and alkalinity are measured using a pH scale for which 7.0 is neutral. The lower a substance's pH (less than 7), the more acidic it is; the higher a substance's pH (greater than 7), the more alkaline it is. Normal rain has a pH of about 5.6; it is slightly acidic because carbon dioxide (CO 2) dissolves into it forming weak carbonic acid. Acid rain usually has a pH between 4.2 and 4.4. Policymakers, research scientists, ecologists, and modelers rely on the National Atmospheric Deposition Programâs (NADP) National Trends Network (NTN) for measurements of wet deposition.