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प्रश्न
How will you check with the help of soap powder whether water is hard?
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उत्तर
- In hard water (from a well or a tube well), soap does not foam but instead creates scum.
- As a result, soap loses its cleaning ability. So, using soap, we can determine that the water is hard.
संबंधित प्रश्न
While preparing soap a small quantity of common salt is generally added to the reaction mixture of vegetable oil and sodium hydroxide. Which one of the following may be the purpose of adding common salt?
(A) To reduce the basic nature of the soap
(B) To make the soap neutral
(C) To enhance the cleansing power of the soap
(D) To favour the precipitation of the soap
In a locality, hard water, required for an experiment, is not available. However, the following salts are available in the school laboratory:
1. Sodium sulphate
2. Calcium sulphate
3. Magnesium chloride
4. Sodium chloride
5. Calcium chloride
6. Potassium sulphate
Which of the above salts may be dissolved in water to obtain hard water for the experiment?
(A) 2, 3 and 5
(B) 1, 2 and 5
(C) 1, 2, 4 and 6
(D) 3 and 5 only
While studying the saponification reaction, what do you observe when you mix an equal amount of colourless vegetable oil and 20% aqueous solution of NaOH in a beaker?
(A) The colour of the mixture has become dark brown
(B) A brisk effervescence is taking place in the beaker
(C) The outer surface of the beaker has become hot
(D) The outer surface of the beaker has become cold
Explain esterification reaction with the help of a chemical equation. Describe an activity to show esterification.
Fill in the following blank with suitable word:
............. is better than soap for washing clothes when the water is hard.
Explain the cleansing action of soap. Draw diagrams to illustrate your answer.
Give the reason of formation of scum when soaps are used with hard water.
A student takes 4 mL of distilled water in each of four test tubes I, II, III and IV, and then dissolves an equal amount of four different salts namely NaCl in I, CaCl2 in II, MgCl2 in III and KCl in IV. He then adds 8 drops of the given soap solution to each test tube and shakes the contents of the test tube 10 times. In which test tubes will enough lather (foam) be formed ?
(A) I and II
(B) II and III
(C) I and IV
(D) III and IV
The saponification of a fat or oil is done using _____ solution for hot process.
Analogy:
Used to join components: Adhesives:: Clean the body ______.
