Litmus "Lecanora tartarea" (Norway, Sweden), "Variolaria dealbata", "Ochrolechia parella", "Parmotrema tinctorum", and "Parmelia". Currently, the main sources are "Roccella montagnei" (Mozambique) and "Dendrographa leucophoea" (California). The main use of litmus is to test whether a solution is acidic or basic. Wet litmus paper can also be used to test for water-soluble gases that affect acidity or alkalinity; the gas dissolves in the water and the resulting solution colors the litmus paper. For instance, ammonia gas, which is alkaline, turn the red litmus paper blue. Blue litmus paper turns red under acidic conditions and red litmus paper turns blue under basic or
SAT Subject Test in Chemistry of 110. The College Board's recommended preparation is a one-year college preparatory course in chemistry, a one-year course in algebra, and experience in the laboratory. However, some second-year algebra concepts (including logarithms) are tested on this subject test. Given the timed nature of the test, one of the keys of the mathematics that appears on the SAT II in Chemistry is not the difficulty, but rather the speed at which it must be completed. Furthermore, the oft-quoted prerequisite of lab-experience is sometimes unnecessary for the SAT Subject Test in Chemistry due to the nature of the questions concerning experiments; most