Unit 2

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Chapter Unit 2

Metal Corrosion, its Prevention and Electrochemistry

1. During corrosion evolution of hydrogen gas occurs in __________*

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basic medium

acidic medium

all of these

neutral medium

2. Waterline corrosion is an example of ____________*

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differential metal corrosion

stress corrosion

differential aeration corrosion

pitting corrosion

3. ___________ corrosion control technique is most suitable in case of buried pipelines.*

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corrosion inhibitors

Cathodic protection

anodic metal coating

anodic protection

4. The process of electroplating involves __________*

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redox reaction

electrolysis

discharge of metal ions at cathode

all of these

5. Welding is a better joining technique then using mechanical fasteners because it prevents _________*

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galvanic corrosion

pitting corrosion

crevice corrosion

Stress corrosion

6. The metal which is commonly used as a coating metal during electroplating of imitation jewellery is *

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Gold

Aluminium

Silver

Rhodium

7. The process due to which water splits into hydrogen ions and hydroxyl ions is *

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Galvanizing

Tinning

Ionization

Electrolysis

8. The method of electrolysis which is used to improve corrosion resistance of any metal *

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Redox reaction

Oxidation

Electroplating

Tinning

9. During electro refining of blister copper, anode and cathode respectively made up of *

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Pure Zn and impure Zn

Pure Mg and impure Mg

Pure Cu and impure Cu

Impure Cu and pure Cu

10. Which type of oxide film is formed on the surface of alkali and alkaline earth metal? *

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Unstable oxide film

Non porous oxide film

Porous oxide film

Volatile oxide film

11. Identify the substance, which form physical barrier between metal and corroding medium and reduce the corrosion *

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Semipermeable membrane

Inhibitors

Promoters

Salt bridge

12. The process used for repairing broken or worn out parts of machine is called *

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Electroplating

Electro refining

Electrometallurgy

Tinning

13. The organic or inorganic substances, which when added in small quantity to the corrosive environment, effectively minimize the corrosion of metal are called as *

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none of these

Negative catalyst

Promoter

Inhibitor

14. On which part of any metal, differential aeration type of corrosion will occur *

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Less oxygenated part

none of these

More oxygenated part

More oxygenated part and Less oxygenated part

15. Electro chemical equivalent of a metal is Y gm/coulomb. The equivalent weight of a metal is *

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Y/96500

96500*Y

96500/Y

Y+96500

16. Name the type of corrosion in the given situation copper sheets joint by iron nails and is exposed to humid environment *

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Atmospheric corrosion

Atmospheric corrosion and Immersed corrosion

Immersed corrosion

none of these

17. In electrochemical cells two half cells are in contact with each other by *

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none of these

Sand bath

Water bath

Salt bridge

18 . In Zn/Zn++//Cu++/Cu cell, electrical energy is generated at the cost of *

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Electrical energy

Thermal energy

Potential energy

Chemical energy

19. One of the method of preventing corrosion of metal by applying protective coating is *

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Fusion

Electro metallurgy

Electroplating

Electro refining

20. Select the volatile oxide film from the given option *

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AlCl3

none of these

FeCl3

MoO3

21. Tin coated metal can be used for *

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Food industries

Cutlery

Machine preparation

none of these

22. Aqueous CuSO4 solution conducts electricity due to presence of *

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Salts

Atoms

Crystals

Ions

23. The process of decomposition of electrolyte in presence of electric current is called *

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Electro refining

Electroplating

Electrolysis

Galvanizing

24. The aluminum metal is corrosion resistance because of formation of oxide film which is*

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Non porous

Unstable

Porous

Volatile

25. The best suitable alloying metal for iron or steel in cutlery is *

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26. Under the humid conditions, the reaction that occur at cathode when iron hinges plated with copper is *

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Catalysis

Oxidation

Reduction

Redox reaction

27. Name the metal used to protect the metal from corrosion by sacrificial anodic protection *

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28. The reaction taking place in oxygen absorption mechanism of iron in presence of neutral aqueous solution in excess supply of oxygen is *

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Fe++ + 2(OH)- --> Fe(OH)2

Cu++ + 2e- --> Cu

Cu --> Cu++ + 2e-

FeSO4 --> Fe++ + SO4- -

29. The product obtain at cathode during electrolysis of aqueous CuSO4 solution using platinum electrode is *

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Deposition of Mg

Deposition of Zn

Deposition of SO4--

Deposition of Cu

30. The metal used in galvanizing to form protective coating on iron sheet is *

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31. One of the method used for the prevention of metal from corrosion by modification of environment is *

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Removal of inhibitor

Removal of corrosion stimulant

Addition of inhibitor

Addition of stimulant

32. In Daniel cell, anode and cathode respectively are made up of *

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Al and Cu

Al and Mg

Zn and Cu

Cu and Zn

33. Name the reaction taking place at anode in Daniel cell *

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none of these

Redox reaction

Reduction

Oxidation

34. Several blocks of Mg are fixed to the bottom of the ship to avoid *

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Weight

Weight and Corrosion

Corrosion

none of these

35. Reduction potential is the measure of tendency of electrode to *

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Gain of proton

Loss of electron

Gain of electron

Loss of proton

36. Relation between chemical equivalent and electrochemical equivalent is *

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96500*C.E.=E.C.E.

C.E.=E.C.E./2

C.E.=96500*E.C.E.

C.E.=E.C.E.

37. During electro refining of blister copper 1% H2SO4 is added to electrolyte *

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To increase ionization

To decrease ionization

To improve its conductivity

none of these

38. Ammonium hydroxide considered as a weak electrolyte as in the aqueous solution it *

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Never ionizes

Weakly ionizes

Highly ionizes

Dissolved completely

39. Which of the following is nonelectrolyte? *

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Ethanol, Glucose, CCl4, kerosene

Aq. CuSO4

Aq. AlCl3

Aq. ZnSO4

40. When aqueous solution of silver nitrate is used as an electrolyte during electrolysis then the ions which moves towards the cathode is *

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NO3-

Zn++

Cu++

Ag+

41. 1 Faraday = *

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9500 coulomb

9650 coulomb

900 coulomb

96500 coulomb

42. The substance which in their aqueous/molten state produces ions & allow the electric current to pass through them are known as *

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Non electrolyte

Electrolyte

Electrode

Cathode

43. The metal which is placed at the top of the electrochemical series is *

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Undergoes oxidation

Undergoes electrolysis

Undergoes reduction

none of these

44. Due to the passage of electric current, the electrolyte undergoes *

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Reduction

Redox reaction

Oxidation

Deposition

45. The aqueous CuSO4 solution allows electric current to pass through it, hence it is called *

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Solute

Non electrolyte

Electrolyte

Solution

46. During electrolysis, the ions moving towards the anode are *

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Cations

Anions

Catalyst

Inhibitors

47. Pitting corrosion in stainless steel can be reduced by adding *

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3-4% Mo

10% Cu

48. Galvanized container are not used for storing food products because *

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Poisonous products are formed

Galvanized container are costly

all of these

Not reacts with Zn

49. Select the inert electrode from the following *

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Zinc

Platinum

Aluminum

Copper

50. Name the weak electrolyte from the following *

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HCl

KOH

NaOH

NH4Cl

51. The non-rechargeable cells are called *

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Secondary cell

Ni-Cd cell

Primary cell

Lead storage cell

52. A piece of gold not react spontaneously with 1.0 M HCl select the correct statement *

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Gold is at the bottom in E.C.S. than H+

Gold is at the top in E.C.S. than H+

none of these

Gold is very active metal

53. During electrolysis 2 ampere of current is passed through CuSO4 & ZnSO4 solution which are connected in series, if amount of Cu deposited is 3.17 gm, calculate the amount of Zn deposited, Given C.E. of Cu is 31.75 & C.E. of Zn is 32.5 *

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32.4 gm

3.24 gm

324 gm

0.324 gm

54. Calculate the weight of a substance deposited when current of 1.5 ampere is passed through solution for 30 minutes, given: E.C.E. =0.000337 *

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0.891 gm

83.3 gm

87.9 gm

89.9 gm

55. Calculate the equivalent weight of substance if its electrochemical equivalent is 0.00032 gm *

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0.31 gm

0.32 gm

30.88 gm

0.308 gm

56. Choose the electrode at which oxidation takes place in electrochemical cell *

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Anode

Cathode

Inert electrode

57. Calculate the time in minutes, when 0.921 gm substance is deposited by passing current of 2.5 ampere through ZnSO4 solution for given ECE of Zn=0.000304 *

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20.19 minutes

1112.2 minutes

1211.84 minutes

none of these

58. Underground part of buried electric pole undergoes corrosion due to *

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Cathodic protection

Differential aeration principle

Sacrificial anodic method

none of these

59. Calculate the chemical equivalent of Zn ,when CuSO4 & ZnSO4 solutions are electrolyzed in series, the weight of a Cu & Zn deposited are 6.35 gm and 6.5 gm respectively.(given :atomic wt. of Cu=63.5 gm) *

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32.5 gm

0.325 gm

325 gm

0.30 gm

60. The electrolytic solution is *

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Electrically neutral

Electrically negative

none of these

Electrically positive

61. The process of attaching more active metal to an iron object for preventing from corrosion is *

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O2 absorption

Sacrificial anode

Cathodic protection

H2 evolution

62. If 96500 coulomb of charge deposited 108 gm of silver, calculate the weight of silver deposited when 9650 coulomb of charge is passed *

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11.8 gm

10.8 gm

110 gm

118 gm

63. The technique particularly used for protection of underground pipeline in industry is called as *

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Impressed current

Sacrificial anode

O2 absorption

H2 evolution

64. In which state the common salt does not conduct electricity? *

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none of these

Liquid

Solid

Gaseous

65. Coating of which metal is anodic on steel according to galvanic cell *

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Co and Mg

none of these

66. The weight of a substance liberated/deposit by passing one faraday of electricity is equal to, *

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Two gram equivalent of substance

one gram equivalent of substance

96500 gm

96500 coulomb

67. Calculate E.C.E. of Cu, if atomic weight of Cu is 63.5 *

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3.3 g/c

0.00

0.033 g/c

0.00033 g/c

68. The chemical reaction in primary cell is *

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Slow

Fast

Irreversible

Reversible

69. In galvanizing process NH4Cl flux is used for avoid _________.*

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none of these

Oxidation

Redox reaction

Reduction

70. Name the mechanism of corrosion in given situation-A metallic structure with two dissimilar metals built in river, polluted with acidic waste from nearby industry __________.*

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Sacrificial anodic method

H2 evolution

none of these

Cathodic protection

71. NaOH is strong electrolyte, as in the aqueous solution it ________.*

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Not ionizes

none of these

Highly ionizes

Feebly ionizes

72. Electrolyte conduct electricity due to presence of *

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Atoms

Electrons

Ions

Crystals

73. Solid NaCl does not undergo electrolysis due to *

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Absence of ions

Cations

Presence of ions

Anions

74. The metal that form unstable oxide film is *

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75. According to faradays second law "the weight of a substance deposited /liberated at a particular electrode is directly proportional to it’s *

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Equivalent weight

Molecular weight

Chemical equivalent and Equivalent weight

Chemical equivalent

76. A team of engineers on inspection of bridge observed that the part of metallic bridge under water is more corroded than one which is above the sea level, the type of corrosion takes place in this case is *

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H2 evolution

O2 absorption

Sacrificial anodic method

Concentration cell

77. Identify the secondary cell in the following *

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none of these

Daniel cell

Dry cell

Ni-Cd cell

78. During electro refining of blister copper, anode mud obtain is consist of *

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Au,Ag

Fe, Sn

79. When two dissimilar metals are electrically connected, then the more active metal becomes, *

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Anode

Anode and cathode

Cathode

none of these

80. The electrolyte used for electroplating of iron spoon with silver is *

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none of these

Ag(OH)2

K(Ag (CN)2)

AlCl3

81. In Daniel cell, the reactions are _____________ *

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Reversible

Fast

Irreversible

Slow

82. Ionic compounds when dissolved in solvent like water produces *

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None

Cations

Anions

Ions

83. In electro refining of blister Cu, the electrolyte is *

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FeCl3

ZnSO4

CuSO4

NaCl

84. The metal used to coat copper wire to protect it from the attack of sulphur before its insulation by rubber is *

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85. Electrochemical equivalent is defined as the weight of a substance deposited/liberated by passing _________ electricity.*

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1 coulomb

35 coulomb

10 coulomb

96500 coulomb

Metal Corrosion, its Prevention and Electrochemistry

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