4) Distilled water

5) mineral water

45. What is the total hardness of water (mmol/L), if its 1 liter contains 40,04 mg of calcium (Ca²⁺) ions and 48.24 mg magnusium (Mg²⁺) ions?

1) 2

2) 3

3) 4

4) 5

5) 6

46. Water hardness is characterized by the presence of dissolved salts of calcium and magnesium bicarbonates, called...

1) Temparary hardness

2) permanent hardness

3) non-carbonate

4) total

5) technical

47. This process is described by the equilibrium constant :

1)

2)

3)

4)

5)

48. What is the temporary hardness of water, if for titration of 100 ml of water was consumed 5.65 mL of 0.02 N hydrochloric acid solution (mmol / L)?

1) 8,85

2) 2,8

3) 4,0

4) 11,3

5) 1,13

49. What is the total hardness of water, if for titration of 50 ml of water was consumed 2.5 ml of 0.025 N solution of EDTA (mmol / L)?

1) 2,20

2) 3,45

3) 2,22

4) 2,75

5) 1,25

50. Calculate the equivalent weight (g/mol) of the oxidant in the reaction:

1) 36,5

2) 43,5

3) 87

4) 63

5) 18,25

51. Calculate the equivalent weight (g/mol) of the reducing agent in the reaction:

1) 160

2) 80

3) 16

4) 32

5) 8

52. Select a typical oxidizing agent:

1) Н₂

2) С

3) iron (II) compounds

4) KMnO4

5) СО

53. Select a typical reducing agent:

1) K₂Cr₂O₇

2) KMnO₄

3) H₂О₂

4) HNO₃

5) Сompound of iron (III) Fe³⁺

54. Redox reactions in which the both oxidizing and reducing agents are composed into one molecule is called:

1) Intermolecular

2) Disproportionation

3) Combustion

4) Diplacement

5) Intramolecular

55. An intramolecular reaction in which the atoms of one element is reduced and simultaneously increase the degree of oxidation state is called:

1) Intermolecular

2) Combustion

3) Disproportionation

4) Diplacement

5) Decomposition

56. An equivalent weight of oxidizer KMnO₄ in a water neutral medium is equal ... (g/mol):

1) 158

2) 79

3) 52,6

4) 31,6

5) 25,02

57. Select the oxidation process:

1)

2)

3)

4)

5)

58. Select the oxidation process:

1)

2)

3)

4)

5)

59. Select the reduction process:

1)

2)

3)

4)

5)

60. Select the reduction process:

1)

2)

3)

4)

5)

61. What is the electrode potential of a half cell consisting of zinc electrode in 0,01М ZnCl₂ aqueous solution at 25°C :

1) -0,76В

2) -0,789В

3) -0,731В

4) -0,701В

5) -0,819В

62. What will be the electrode potential at an aluminium electrode, dipped in a 0,001М AlCl₃ aqueous solution at 25°C :

1) -1,64В

2) -1,84В

3) -1,719В

4) -1,601В

5) -1,54В

63. Calculate the electrode potential at an gold electrode, dipped in a 0,001М aqueous solution of gold salt at 25°C :

1) +1,441В

2) +1,559В

3) -1,45В

4) +1,557В

5) +1,481В

64. The electrode potential at an copper electrode, dipped in a 0,01М aqueous solution of copper sulfate at 25°C, is equal ....... :

1) +0,34В

2) +0,399В

3) +0,311В

4) +0,369В

5) +0,281В

65. What the metal cations will be recovered from their salt solutions by iron?

1) Ca, Cu

2) Al, Cu

3) Sn, Pb

4) Mn, Ni

5) Zn, Mn

66. What the metal cations will be recovered from their salt solutions by magnesium?

1) Zn, Mn

2) Ca, Na

3) Cu, K

4) Ag, Ca

5) Li, Sn

67. From a mixture of cations in the solution are recovered in the first place:

1) Metals with the lowest value of the electrode potential