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
AP Chemistry or honors level High School Chemistry may also be waived, but usually requires completion of a special assignment or exam. The exam covers most of the introductory chemistry topics (except organic chemistry), including: The annual AP Chemistry examination, which is typically administered in May, is divided into two major sections (multiple-choice questions and free response essays). The old test was composed of two sections: a multiple-choice section consisting of 75 questions with five answer choices each, and a free-response section consisting of six essay prompts that required the authoring of chemical equations, solution of problems, and development of thoughtful essays