c7SciCh2no NCERT GUIDE CLASS 7 Chapter 2. Exploring Substances: Acidic, Basic, and Neutral NCERT CLASS-7 GUIDE Notes in a Nutshell Substances around us may be classified as acidic, basic, and neutral in nature. Litmus Paper and its Use. - Litmus is a natural substance obtained from lichens. It is available both as a solution and in the form of paper strips, known as litmus paper. - The litmus paper is available in two colours—blue and red. - Substances that turn blue litmus paper to red are acidic in nature, while those that turn red litmus paper to blue are basic in nature. Acidic substances: turn blue litmus red. Basic substances: turn red litmus blue. - Since litmus shows different colours in acidic and basic solutions, it is called an acid-base indicator. Some substances other than litmus, both natural and synthetic, can also be used as indicators. Synthetic indicators are mad...
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