Advertisements
Advertisements
प्रश्न
Someone put some universal indicator paper onto wet soap. The pH is 8. What does this tell you about the soap?
उत्तर
Universal indicator paper put onto wet soap shows pH 8, indicating that wet soap is a base. Bases show a value above 7 on the pH scale.
APPEARS IN
संबंधित प्रश्न
Under what soil condition do you think a farmer would treat the soil of his fields with quick lime (calcium oxide) or slaked lime (calcium hydroxide) or chalk (calcium carbonate)?
What colours do the following indicators turn when added to an acid (such as hydrochloric acid)?
litmus
(b) Name the acid or alkalis used to make (i) car batteries (ii) explosives (iii) soaps (iv) fertilisers.
Name two common antacids.
The daffodil plants grow best in a soil having a pH range of 6.0 to 6.5. If the soil in a garden has a pH of 4.5, which substance needs to be added to the soil in order to grow daffodils?
(a) salt
(b) lime
(c) sand
(d) compost
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 _______.
Acids and bases can be identified in the laboratory by ______.
Write a note on:
Phenolphthalein
Using the knowledge of acids and bases, write a secret message with the help of baking soda and beet root. Explain how it works.
(Hint: Prepare baking soda solution in water. Use this solution to write the message on a sheet of white paper with a cotton bud. Rub a slice of fresh beetroot over the message.)
