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प्रश्न
A solution turns blue litmus red. Its pH is likely to be:
(a) 7
(b) 5
(c) 8
(d) 14
उत्तर
5
An acidic solution turns blue litmus red. On the pH scale, acids have values less than 7, whereas bases have values greater than 7. Solutions with pH equal to 7 are neutral in nature. Therefore, the pH of the given solution is likely to be 5.
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संबंधित प्रश्न
Three liquids are given to you. One is hydrochloric acid, another is sodium hydroxide and the third is a sugar solution. How will you identify them? You have only turmeric indicator.
The indicators which turn red in acid solution are:
(a) turmeric and litmus
(b) phenolphthalein and methyl orange
(c) litmus and methyl orange
(d) phenolphthalein and litmus
The pH of a cold drink is 5. What will be its action on blue and red litmus solutions?
Under what soil conditions do you think a farmer would treat the soil of his fields with quicklime (calcium oxide), or slaked lime (calcium hydroxide) or chalk (calcium carbonate)?
Someone put some universal indicator paper onto wet soap. The pH is 8. What does this tell you about the soap?
A solution turns phenolphthalein indicator pink. The most likely pH of this solution will be:
(a) 6
(b) 4
(c) 9
(d) 7
Which of the following elements would from oxides which would indicate pH values less than seven, using moist pH paper?
Magnesium, Carbon, Sulphur, Hydrogen, Copper
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?
Turmeric is used as a _______.
State whether the following statements are true or false. Correct the false statements.
Phenolphthalein is a natural indicator.
