1 Answers
Option 1 : Red cabbage leaves and turmeric
Concept:
Acids and bases:
| Acids | Bases |
| They are sour in taste. | They are bitter in taste and soupy to touch |
| The pH of acids is below 7. | The pH range of bases falls above 7 |
| Acids turn blue litmus red | Bases turn red litmus blue. |
| Examples - Vinegar, lemon juice, etc. | Examples - Soup solution, neem, clove, etc. |
Acid-base Indicator:
- Acid-base indicators are dyes or mixtures of dyes that are used to indicate the presence of acids and bases.
- Examples of Natural Indicators of acid and base are:
- Litmus paper
- Red cabbage leaves
- Turmeric
- China rose
| Red Litmus | Blue Litmus | |
| Acidic solution | Stays red | Turns red |
| Neutral solution | Stays red | Stays blue |
| Alkaline solution | Turns blue |
Stays blue |
- Examples of synthetic Indicators of acid and base are:
- Methyl orange
- Phenolphthalein.
| Indicator | Acidic | Neutral | Alkaline |
| Methyl orange | Red | Neutral | Yellow |
| Phenolphthalein | Colorless | Colorless | Pink |
Explanation:
- Red cabbage leaves are a natural acid-base indicator and it is red in color. the red cabbage leaves remain red in acidic solutions but turn green on adding to basic solutions.
- Similarly, turmeric is also a natural acid-base indicator. It contains a yellow dye and remains yellow in an acidic medium but it turns red in a basic solution.
- Salt is neither acid nor base. It is formed by the reaction between acid and salt. Hence, indicators do not affect salt.
- Banana leaves contain a little bit of acid but it does not change color when the solution turns acidic or basic. Hence, it is not an acid-base indicator.
- Lemon juice contains citric acid and it is an olfactory indicator Hence, it is not an acid-base indicator.
Thus, we can say that the correct answer is Red cabbage leaves and turmeric.
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