AP BIOLOGY

Detailed explanation-1: -Acids turn blue litmus paper red and bases turn red litmus paper blue. Nitric acid turns blue litmus red since it is an acid. So, the given statement is false.

Detailed explanation-2: -Litmus is mainly used to assess whether a solution is acidic or basic. The colour transition occurs over the pH range 4.5–8.3 at 25 °C (77 °F), with light blue litmus paper turning red under acidic conditions and red litmus paper turning blue under basic or alkaline conditions.

Detailed explanation-3: -The fastest way to determine pH is to use pH paper. It uses a broad range indicator to turns a series of colors from pH 1 to 14. The color change is then compared with a color chart to determine the pH. A high pH indicates a base, and a low pH indicates an acid.

Detailed explanation-4: -YES, Litmus is the most commonly used natural indicator which is extracted from lichens. It has a mauve color in distilled water. It turns red when added to an acidic solution & turns blue when added to a basic solution.

Detailed explanation-5: -The paper is treated with a chemical known as Flavin which is soluble in water and changes color in the presence of various types of solutions. In the presence of an acidic solution, the paper turns red. In the presence of alkaline solutions, the paper turns a greenish-blue.