Ncert Solutions Chemistry Class 11th
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9.41. Assertion: Hard water is desirable for laundry.
Reason: Soap containing sodium stearate (C17H35COONa) reacts with hard water to precipitate out Ca/Mg stearate.
9.41. Assertion: Hard water is desirable for laundry.
Reason: Soap containing sodium stearate (C17H35COONa) reacts with hard water to precipitate out Ca/Mg stearate.
9.41. (d) Hard water forms scum/precipitate with soap. Soap containing sodium stearate (C17H35COONa) reacts with hard water to precipitate out Ca/Mg stearate.It is, therefore, unsuitable for laundry. It is harmful for boilers as well, because of deposition of salts in the form of scale. This r
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9.40. Assertion: An ice cube floats on water.
Reason: Density of ice is more than that of water.
9.40. Assertion: An ice cube floats on water.
Reason: Density of ice is more than that of water.
9.40. (c) The crystalline form of water is ice. Atatmospheric pressure ice crystallises in the hexagonal form, but at very low temperatures it condenses to cubic form. Density of ice is less than that of water. Therefore, an ice cube floats on water. In winter season ice formed on the su
Upvote 9.39. Assertion: Lithium hydride used in the synthesis of other useful hydrides.
Reason: Lithium hydride is very reactive at moderate temperatures with O2 or Cl2.
9.39. Assertion: Lithium hydride used in the synthesis of other useful hydrides.
Reason: Lithium hydride is very reactive at moderate temperatures with O2 or Cl2.
9.39. (c) Lithium hydride is rather unreactive atmoderate temperatures with O2 or Cl2. It is, therefore, used in the synthesis of other usefulhydrides, e.g.,
8LiH + Al2Cl6 → 2LiAlH4 + 6LiCl
2LiH + B2H6 → 2LiBH4
Upvote 9.38. Assertion: H+ does not exist freely and is always associated with other atoms or molecules.
Reason: H+ form hydrides.
9.38. Assertion: H+ does not exist freely and is always associated with other atoms or molecules.
Reason: H+ form hydrides.
9.38. (b) Loss of the electron from hydrogen atomresults in nucleus (H+) of ~1.5×10–3 pm size.This is extremely small as compared to normalatomic and ionic sizes of 50 to 200pm. As a consequence, H+ does not exist freely and isalways associated with other atoms ormolecules.
Upvote Assertion and Reason:
Directions:
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.
9.37. Assertion: H2O2 is stored in wax-lined glass or plastic vessels in dark.
Reason: H2O2 decomposes slowly on exposure to light.
Assertion and Reason:
Directions:
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.
9.37. Assertion: H2O2 is stored in wax-lined glass or plastic vessels in dark.
Reason: H2O2 decomposes slowly on exposure to light.
9.37. (a) H2O2 decomposes slowly on exposure to light.
2H2O2 (l) → 2H2O (l) + O2 (g)
In the presence of metal surfaces or traces ofalkali (present in glass containers), the above
reaction is catalysed. It is, therefore, stored inwax-lined glass or plastic vessels in dark.
Upvote 9.36. What do you understand by the terms:
(i) Hydrogen economy
(ii) Hydrogenation
(iii) Syngas
(iv) Water-gas shift reaction
(v) Fuel-cell?
9.36. What do you understand by the terms:
(i) Hydrogen economy
(ii) Hydrogenation
(iii) Syngas
(iv) Water-gas shift reaction
(v) Fuel-cell?
9.36. (i) Hydrogen economy: The basic principle of hydrogen economy is the storage and transportation of energy in the form of liquid or gaseous dihydrogen.
(ii) Hydrogenation: Hydrogenation means addition of hydrogen across double and triple bonds in presence of catalyst to form sat
Upvote 9.35. Bleaching action of H2O2 is due to the oxidation of colouring matter by nascent oxygen.
H2O2→ H2O + O
Upvote 9.34. Do you expect different products in solution when aluminium (III) chloride and potassium chloride treated separately with (i) normal water (ii) acidified water, and (iii) alkaline water? Write equation wherever necessary.
9.34. Do you expect different products in solution when aluminium (III) chloride and potassium chloride treated separately with (i) normal water (ii) acidified water, and (iii) alkaline water? Write equation wherever necessary.
9.34. KCl is a salt of strong acid HCl and strong base KOH. Such salts are neutral in nature and do not undergo hydrolysis. In neutral water, acidic water, and alkaline water, KCl dissociates as
Water
KCl → ?K++Cl−
AlCl3? is a salt of strong acid HCl and weak base&nb
Upvote 9.33. What do you expect the nature of hydrides is, if formed by elements of atomic numbers 15,19, 23 and 44 with dihydrogen? Compare their behaviour towards water.
9.33. What do you expect the nature of hydrides is, if formed by elements of atomic numbers 15,19, 23 and 44 with dihydrogen? Compare their behaviour towards water.
9.33. Atomic number 15 is of phosphorus. The hydride is PH3 and its nature is covalent. Atomic number = 19 is of potassium. The hydride is KH and it is ionic in nature. Atomic number = 23 is of vanadium. The hydride is VH. It is interstitial or metallic. Atomic number =44 is of ruthenium,
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