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प्रश्न
Fill in the following blank with suitable words:
Alkalis have a pH.............. than 7.
उत्तर
Alkalis have a pH greater than 7.
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संबंधित प्रश्न
Blue litmus paper is dipped in a solution. It remains blue. What is the nature of the solution? Explain.
How does a universal indicator work?
The pH values of six solutions A to F are given below:
A = 0, B = 11, C = 6, D = 3, E = 13, F = 8
Which of the above solutions are (i) acids (ii) alkalis?
The pH values of five solutions A, B, C, D and E are given below:
| A | 1 |
| B | 5 |
| C | 7 |
| D | 11 |
| E | 13 |
Solution A turns universal indicator blue to purple whereas solution B turns universal indicator orange to red.
Name any two substances which can give solutions like B.
Solution A turns universal indicator blue to purple whereas solution B turns universal indicator orange to red.
What sort of reaction takes place when solution A reacts with solution B?
A group of students measured the pH of some substances they found in their homes. Their results are given in the following table:
| Substance | pH | Substance | pH |
| Apples | 3.0 | Salt | 7.0 |
| Baking soda | 8.5 | Sugar | 7.0 |
| Black coffee | 5.0 | Toothpaste | 9.0 |
| Household ammonia | 12.0 | Vinegar | 3.0 |
| Lemon juice | 2.5 | Washing soda | 11.5 |
| Milk | 6.5 |
(a) What would the students have used to measure the pH?
(b) Which solution is the most acidic?
(c) Which solution is the most alkaline?
(d) Which solutions are neutral?
(e) Which solution can be used to treat wasp stings?
(f) Which solutions can be used to treat bee stings?
Neutral substances do not bring about any change in colour of indicators.
Assertion: Methyl orange and phenolphthalein are natural indicators.
Reason: Methyl orange is yellow in colour while phenolphthalein is pink.
Write a note on:
Methyl orange
