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प्रश्न
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
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उत्तर
Soap molecules are sodium or potassium salts of long-chain carboxylic acids. On reaction with calcium or magnesium ions, the soap solution forms insoluble precipitates. However, the formation of foam by the soap solution is hardly influenced by the presence of sodium and potassium ions.
Thus, after adding soap to each test tube and shaking them well, a good amount of lather will be formed in the test tubes marked I and IV.
Hence, the correct option is C.
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संबंधित प्रश्न
Would you be able to check if water is hard by using a detergent?
A student took four test tubes P, Q, R and S and filled about 8 mL of distilled water in each. After that he dissolved an equal amount of Na2SO4 in P, K2SO4 in Q, CaSO4 in R and MgSO4 in S. On adding an equal amount of soap solution and shaking each test tube well, a good amount of lather will be obtained in the test tubes:
(a) P and Q
(b) P and R
(c) P, Q and S
(d) Q, R and S
A student requires hard water for an experiment in his laboratory which is not available in the neighbouring area. In the laboratory there are some salts, which when dissolved in distilled water can convert it into hard water. Select from the following groups of salts, a group, each salt of which when dissolved in distilled water will make it hard.
(A) Sodium chloride, Potassium chloride
(B) Sodium sulphate, Potassium sulphate
(C) Sodium sulphate, Calcium sulphate
(D) Calcium sulphate, Calcium chloride
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The chemical mostly used in the preparation of most of the soaps we use is
(a) Sodium chloride
(b) Potassium hydroxide
(c) Sodium hydroxide
(a) Potassium chloride
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Distinguish between esterification and saponification reactions of organic compounds.
Give a scientific explanation.
Soap forms a precipitate in hard water.
Analogy:
Used to join components: Adhesives:: Clean the body ______.
The soap molecule has a
