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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
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(a) rain
(b) tap
(c) hand pump
(d) pond
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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