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In a Nutshell
| NCERT Point | Simple Meaning |
|---|---|
| Substances around us may be classified as acidic, basic, and neutral in nature. | Three types of substances |
| Extracts of lichen, red rose, red hibiscus, purple cabbage, turmeric, etc., can be used to indicate the nature of substances. | Natural substances show acid-base |
| Substances that show different colours in acidic and basic solutions are called acid-base indicators. | Indicators change colour |
| Acids turn the colour of blue litmus to red. Bases turn the colour of red litmus to blue. | Litmus shows acid-base nature |
| Extract of red rose gives red colour in acidic solutions and green colour in basic solutions. | Red rose changes colour |
| The yellow colour of turmeric turns red in basic solutions but remains unchanged in acidic and neutral solutions. | Turmeric detects only bases |
| An acid and a base neutralise each other, forming salt and water, along with the evolution of heat. | Acid plus base makes salt |
| Many day-to-day problems like a red ant bite, acidic or basic nature of soil, and industrial waste can be attempted to be managed by the process of neutralisation. | Neutralisation solves daily problems |
Quick Revision Table
| Term | Simple Meaning |
|---|---|
| Acid | Sour substance turns litmus red |
| Base | Bitter slippery turns litmus blue |
| Neutral | Neither acidic nor basic |
| Indicator | Shows acid or base nature |
| Litmus | Natural indicator from lichens |
| Neutralisation | Acid plus base makes salt |
| Formic acid | Acid in ant bite |
| Olfactory indicator | Smell changes with acid-base |
