Electro chemistry

Multiple choice Questions:- 1) In an electro chemistry cell the electrical energy is

obtained at the cost of

a) Mechanical energy

b) internal energy

c) chemical energy

d) Thermal energy

Ans: (c)

c) chemical energy

2) The device used to bring about non-spontaneous red px

reactions by supplying electrical energy is called

a) electrochemical cell

b) electrolytic cell

c) dry cell

d) De

Ans: (b)

b) electrolytic cell

3) Some statements are given below

a) The electrolytic conduction is due to the migration

of ions through the electrolyte

b) The postage of electric current through the

electrolyte leads to the chemical changes

c) Electrolysis is a spontaneous redox reaction.

d) Sodium chroride carries electricity only in its

aquarous solution.

(Among the above the correct statements are)

Ans : (c)Ans : (c)

c) Electrolysis is a spontaneous redox reaction.

4) One & araday of electricity liberates the amount of ions

which is equal to its

a) molecular weight

b) atomic weight

c) equivalent weight

d) none of these

Ans: (a)

a) molecular weight

5) The atomic weight of Cu is 64. The weight Cu liberated

from CuSo4 solution by passing a current of 0.965

ampere for 1000 seconds would be

a) 0.64 g

b) 0.64 kg

c) 0.32 kg

d) 0.32 x 103 kg

Ans : (a)

a) 0.64 g

6) Some statement are given below

a) The weight of on ion liberated during electrolysis is directly proportional to the quantity of current passed.

b) Coulomb is the product of current in ampere and time.

c) the weight of substance formed at the electrode by the same amount of electricity is proportional to the equivalent weight of that substance

d) The minimum weight of that substance which can be obtained during electrolysis is its electrochemical equivalent

(Among the above the false statement are a, b & d)

Ans: (c)

c) the weight of substance formed at the electrode by the same amount of electricity is proportional to the equivalent weight of that substance

7) The atomic weight of Al is ‘X’ the electrochemical

equivalent of Al in the solution of Aluminium sulphate will

be

a)3X/F

b) X/3F

c) 2X/F

d) X/F

Ans : (b)

b) X/3F

8) The current of 5000 MA is passed through a solution for

10 seconds. The no. of coulombs passed are

a) 50000

b) 500

c) 5000

d) 50

Ans : (d)

d) 50

9) The No. of coulombs required to liberate 0.224 dm3 of

chlorine at 00C @ 1 atm (NTP) pressure is

a) 2 X 965

b) 965/2

c) 965

d) 9650

Ans: (a)

a) 2 X 965

10) The No. of coulombs required to liberate 1.12 dm3 of H2

at 2730C and 2 atm pressure is

a) 2 X 9650

b) 9650

c) 4 X 9650

d) 965

Ans: (c)

c) 4 X 9650

11) The volume of O2 at STP by the passage of 2 for a day

of electric charge through acidulated water is

a) 22.4 Lit.

b) 5.6 Lit.

c) 11.2 Lit.

d) 2.24 Lit.

Ans: (c)

c) 11.2 Lit.

12) The volume of H2 liberated at 2730C and at atm

pressure by the passage of 1 Euroaday of electricity

through HCL solution is

a) 11.2 dm3

b) 22.4 dm3

c) 44.8 dm3

d) 5.6 dm3

Ans: (b)

b) 22.4 dm3

13) 2 X 10-3 kg of on element i.e. deposited by passing 2A

current for 16 min and 5 second through a solution.

The equivalent weight of the element is

a) 100 b) 50

c) 25 d) 200

Ans: (a)

a) 100

14) The chemical equivalent of the element A,B and C are

4,12 and 20 respectively. The weight of A, B and C

liberated by 1000 coulomb will be in the rating of

a) 5 : 3 : 1

b) 1 : 3 : 5

c) 1 : 1 : 1

d) 1 : 2 : 2

Ans : (b)

b) 1 : 3 : 5

15) The electro chemical equivalent of metal A and B are in

the ratio of X:Y. If a given quantity of electricited

deposit & weight of A, the weight of B deposited by the

same quantity of electricity would be

a) WY/X

b) WY/Wxg

c) Wg.

D) WX/Yxg

Ans: (a)

a) WY/X

16) The atomic weight of elements x and y are in the ratio

of 1:2 coulombs deposit equal weights of these two

elements. Then ik valency of x is 2 that of y is

a) 2

b) 1

c) 4

d) 3

Ans : (c)

c) 4

17) If the current of x ampere is passing through a solution

for t min. The number faradays passing are

a) 60 xt

b) xt

c) 60xt / 96500

d) xt / 96500

Ans : (c)

c) 60xt / 96500

18) One horse power is equal to

a) 1000 J

b) 647 watt

c) 746 Watt

d) 1000 KJ

Ans: (c)

c) 746 Watt

19) Some statement are given below

A) Joule is the unit of work

B) Faraday is the unit of electric current

C) Watt is the work performed at the rate of 1 Joule

per second

D) Volt = Ohm x Ampere

Among the above the true statements are

a) only A & C b) only A,B & D

c) only A,C & D d) all

Ans : (c)

c) only A,C & D

20) The cell reaction of the Daniall cell in the standard state can be correctly represented as

a) Zn (s) + Cu2- (aq) Zn2+ (aq) + Cu (s)

b) Zn (s) + Cu2- (aq) (1M) Zn2+ (aq)(1M) + Cu (s)

c) Zn (s) + Cu2- Zn2+ + Cu (s)

d) Zn2- (aq)(1M) + Cu (s) Zn (s) + Cu2+ (aq)(1M)

Ans : (b)

b) Zn (s) + Cu2- (aq) (1M) Zn2+ (aq)(1M) + Cu (s)

21) During the working of the Daniell cell, which of the following happens

a) The size of the Zn rod remains same but the blue colour of CuSo1 solution becomes faint

b) The size of the Zn rod is reduced and the blue colour of CuSo4 solution becomes faint.

c) The size of the Zn rod reduced but there is no change in the intensity of colour of the CuSo4 solution.

d) The size of the Zn rod as well as the intensity of the colour of CuSo4 solution remain unchanged.

Ans: (b)

b) The size of the Zn rod is reduced and the blue colour of CuSo4 solution becomes faint.

22) Some Statements are given belowA) In an electrochemical cell oxidation takes place at anode.B) In an electrochemical cell reduction takes place at cathode.C) In takes Daniell cell the Cu electrode grows in size during the working of the cell.D) The salt bridge maintains electrical neutrality of the half -cell ionic solutions.Among the above the wrong statement is

a) Only B b) Only Cc) Only A d) None

Ans : (d)

d) None

23) 25. In the cell; Pt, O2 (g)| OH- || Cl- | Cl2 (g) Pt, the

anode half cell reaction is

a) OH ½ O2 + ½ H2 + e

b) 2OH O2 + H2 + 2e

c) 2OH ½ O2 + H2O + 2e

d) ½ O2 + H2O + 2e 2OH

Ans : (c)

c) 2OH ½ O2 + H2O + 2e

24) In a saturated calomel electrode the KCl solution is

saturated with

a) Only KCl

b) Only calomel

c) Both KCl and calomel

d) None

Ans : (c)

c) Both KCl and calomel

25) The potential of a calomel electrode depends on

a) concentration of KCl only

b) temperature only

c) both, the concentration of KCl and temperature

d) its construction.

Ans : (c)

c) both, the concentration of KCl and temperature

26) The standard reduction potential of the metal A, B and

C are in decreasing order. Which of these will always

behave as the anode when coupled with the other two

separately to form a cell ?

a) A b) B

c) C d) can not be predicted

Ans : (c)

c) C

27) The S.O.P values of metals A, B and x and y

respectively. If x > y, the standard EMF of the cell

containing these electrodes would be

a) x – y

b) y – x

c) x + y

d) unpredictable

Ans: (a)

a) x – y

28) The metals X, Y and Z follow one another in the same

order in the E.M.F. series of S.O.P. On this basis

some statements are made below

A) The ease of oxidation is in the order X > Y > Z

B) The reducing power decreases in the order X > Y > Z

C) X will displace Y and Z from their solutions.

D) The maximum E.M.F. if the cell will be obtained by using

X and Y as electrodes.

Among the above the correct statements are

a) Only A, B & D b) Only A, C & D

c) Only A, B & C d) All

Ans : (c)

c) Only A, B & C

29) When electricity is passed through a solution of AlCl3,

13.5 g of Al (At. Wt. 27) is deposited. The number of

Faradays passed through the solution must be

a) 0.5 b) 1

c) 1.5 d) 2

Ans: (c)

c) 1.5

30) Faraday’s laws of electrolysis are concerned with

a) equivalent weight

b) atomic weight

c) molecular weight

d) atomic number

Ans : (a)

a) equivalent weight

31) Which of the following will decompose by passing

current through its aqueous solution ?

a) glucose b) ethanol

c) urea d) silver nitrate

Ans : (d)

d) silver nitrate

32) In electrolysis, oxidation takes place at

a) anode

b) cathode

c) both, at the anode and at the cathode

d) the surface of the solution

Ans : (a)

a) anode

33) 41. No. of faradays required to generate one gm atom of Mg from MgSO4 solution is

a) 1 b) 2c) 3 d) 4

Ans : (b)

b) 2

34) During electrolysis of NaCl, the reaction Na+ +e- Na

takes place at

a) anode and called electronation.

b) anode and called reduction.

c) cathode and called oxidation.

d) cathode and called electronation.

Ans: (d)

d) cathode and called electronation.

35) The atomic weight of Al is 27. The weight of aluminium

deposited by a passage of 5 Faradays through

aqueous Al2 (SO4)3 solution will be

a) 27 g.

b) 9 g.

c) 45 g.

d) 36 g.

Ans : (c)

c) 45 g.

36) During the electrolysis of the aqueous solution of NaCl

the reaction taking place at anode is

a) oxidation of sodium ions.

b) oxidation of chloride ions.

c) reduction of chloride ions.

d) reduction of sodium ions.

Ans: (b)

b) oxidation of chloride ions.

37) Weight of copper deposited by the passage of 2 Faradays of electricity through the aqueous solution of cupric ions is equal to its

a) atomic weightb) molecular weight c) electrochemical equivalent weightd) equivalent weight

Ans: (a)

a) atomic weight

38) The number of electrons involved in the reaction by

passing one Faradays an electrolyte is

a) 96500 b) 12 X 1023

c) 6 X 1023 d) 96500 X 6 X 1023

Ans: (c)

c) 6 X 1023

39) The number of coulombs equal to one Faraday is

a) 95600 b) 96500

c) 95500 d) 93600

Ans: (b)

b) 96500

40) During the electrolysis of NaCl solution the gas

liberated at cathode is

a) Cl2 b) H2

c) O2 d) H2 and O2

Ans: (b)

b) H2

41) The amount of an ion discharged during electrolysis

in not directly proportional to

a) Time

b) strength of current

c) equivalent weight

d) concentration of solution

Ans: (d)

d) concentration of solution

42) Faraday’s laws of electrolysis will fail if

a) temperature is changed

b) inert electrodes are used

c) concentration of the solution is changed

d) none of these

Ans: (d)

d) none of these

43) The unit of electrochemical equivalent is

a) gram/sec b) gram/ampere

c) gram/coulomb d) gram/Faraday

Ans: (c)

c) gram/coulomb

44) The atomic weight of Al is 27. The ECE of Al in AlCl3

solution is

a) b)

c) d)

Ans: (d)

96500

2796500

327

27

9650096500

9

96500

9

45) The charge needed to liberate 0.5 gm atomic weight of

a divalent element is

a) 96500 C b) 48250 C

c) 2 Faraday d) 5 Faraday

Ans: (a)

a) 96500 C

46) The molten electrolyte conducts electricity due to the

presence of

a) free electrons b) free ions

c) free molecules d) free atoms

Ans: (c)

b) free ions

47) A solution of electrolyte in water, when electrolysed,

liberated H2 at the cathode and Cl2 at the anode. The

electrolyte must be

a) H2SO4 b) CuCl2

c) NaCl d) Na2SO4

Ans: (c)

c) NaCl

48) In electrolysis of a fused salt, the weight of a substance

liberated at the electrode is independent of

a) temperature

b) current intensity

c) electrochemical equivalent of ion

d) time for electrolysis

Ans: (a)

a) temperature

49) A certain current liberates 0.504 x 10-3 kg of H2 in a

certain time. The weight of copper (at wt. 63.6)

liberated by the same current in the same time from

CuSO4 Solution is

a) 15.9 kg b) 63.6 kg

c) 31.8 x 10-3 d) 15.9 x 10-3 kg

Ans: (d)

d) 15.9 x 10-3 kg

50) Current is passed through the solutions of silver nitrate

and copper sulphate connected in series. The weight

of Ag (At wt. 108) deposited in 10.8 g. The weight of

Cu (At wt. 64) deposited will be

a) 6.4 g b) 3.2 g

c) 1.6 g d) 10.8 g

Ans: (b)

b) 3.2 g

51) When the same quantity of electricity is passed through

different electrolysis the weights of elements deposited

are in the ratio of their

a) At. No. b) At. Wt.

c) Sp. gravity d) ECE

Ans: (d)

d) ECE

52) 3.5 Faradays of electricity are passed through a

solution of CuSO4. The no. of gm. Equivalent of Cu

deposited will be

a) 3.5 b) 1.75

c) 7 d) 1

Ans: (a)

a) 3.5

53) A current of “ I ” amperes is passed through the

solution of an electrolyte for time “ t min”, when m g of a

substance is liberated at the electrode. The ECE of the

substance is equal to

a) b)

c) d)

Ans: (d)

t

mm

IT

60It

m60m

It

60m

It

54) The amount of Ag (at. Wt 108) deposited by the

current, which deposits 3.2 of O2 is

a) 10.8 g b) 43.2 g

c) 21.6 g d) 3.2 g

Ans: (b)

b) 43.2 g

55) The given amount of current is passed through the cells

placed in series containing the solutions of AgNO3,

NiCl2 and CrCl3. The amounts of Ag (at. Wt. 108), Ni

(at. wt. 60) and Cr (at. Wt. 51) liberated will be in the

ratio of

a) 108:60:51 b) 108:30:25.5

c) 108:20:25.5 d) 108:30:17

Ans: (d)

d) 108:30:17

56) The reference electrolyte is made from

a) ZnSO4 b) CuSO4

c) Hg2Cl2 d) HgCl2

Ans: (c)

c) Hg2Cl2

57) The S.O.P. values of metals are in the following order :

Zn>Cd>Ni>Cu>Ag. On the basis of this, some

statements are made below

A) A solution of CuSO4 is stirred with Zn rod

when

the blue colour of the solution fades.

B) Cu displaces Ni from NiSO4 Solution.

C) Maximum EMF of the cell is obtained by using

Zn

and Ag as electrodes.

D) Ag will displace all the others from their

solutions.

Then from the above

a) Only D is false b) B is false

c) A and D are true d) B and C are true.Ans: (b)

b) B is false

58) When a copper wire is dipped in a solution of AgNO3,

the colour of the solution becomes blue because

copper

a) is oxidized to Cu2+ which enter the solution.

b) is reduced to Cu+

c) enters the solution as copper atoms.

d) cannot displace Ag from the solution.

Ans: (a)

a) is oxidized to Cu2+ which enter the solution.

59) The S.R.P. of Mg and Cu are – 2.30 V and +0.337 V

respectively, then which of the following is wrong?

a) Mg can displace H2 from acids.

b) Mg can displace Cu from CuSO4 Solution.

c) Cu will displace H2 from acids.

d) Cu can not displace Mg from MgCl2

Solution.

Ans: (c)

c) Cu will displace H2 from acids.

60) A depolariser used in a dry cell is

a) ammonia chloride

b) Manganese dioxide

c) Potassium chloride

d) saw dust

Ans: (b)

b) Manganese dioxide

61) The colourless aqueous solutions of the following salts

are placed in separate test tubes and a Cu strip

immersed in each of them. Which solution will finally

turn blue?

a) Pb(NO3)2 b) Zn(NO3)2

c) AgNO3 d) Cd(NO3)2

Ans: (c)

c) AgNO3

62) If an iron rod is placed in a solution of copper sulphate

a) copper will precipitate out.

b) iron will precipitate out.

c) iron and copper both will dissolve.

d) No reaction will take place.

Ans: (a)

a) copper will precipitate out.

63) A calomel electrode is

a) standard hydrogen electrode

b) Reference electrode

c) Platinum electrode

d) Mercury electrode

Ans: (b)

b) Reference electrode

64) A decinormal calomel electrode contains

a) N / 10 solution Hg2Cl2

b) 1 N solution of KCl

c) 1 N solution Hg2Cl2

d) N / 10 solution KCl

Ans: (d)

d) N / 10 solution KCl

65) In an aqueous solution, H2 will not reduce

a) Fe3+

b) Cu2+

c) Zn2+

d) Ag+

Ans: (c)

c) Zn2+

66) The electric charge for the deposition of one

equivalent of a substance, during electrolysis is

a) One ampere for 9650 seconds.

b) 96500 ampere for one hour.

c) One ampere for one hour.

d) Charge on one mole of electrons.

Ans: (d)

d) Charge on one mole of electrons.

67) Following are the actual observations made in the

laboratory.

i) C does not react with the solution of salt of B

ii) B dissolves in the solution of the salt of A

iii) A does not react with the solution of the salt

of C

The reducing power of these metals is in the

order

a) A > B > C

b) C > B > A

c) B > C > A

d) B > A > CAns: (c)

c) B > C > A

68) The standard reduction potentials of A, B and C are

- 0.76 V, + 0.80 V and + 0.34 V respectively. The

reducing power decreases in the order

a) A > B > C

b) C > B > A

c) A > C > B

d) B > C > A

Ans: (c)

c) A > C > B

69) The standard potentional for the reaction,

2H+ (ag) + 2e- H2 (g), is

a) 0 V

b) 1 V

c) – 1V

d) none of these

Ans: (a)

a) 0 V

70) If a salt bridge is removed from between the two half

cells, the EMF

a) drops to zero

b) does not change

c) decreases gradually

d) increases gradually

Ans: (a)

a) drops to zero

71) During the charging of lead storage battery, the

reaction at anode is

a) Pb2+ + SO2-4 PbSO4

b) PbSO4 + H2O PbO + SO2-4 + 2H+

c) Pb Pb2+ + 2e-

d) Pb2+ + 2e- Pb

Ans: (d)

d) Pb2+ + 2e- Pb

72) The metal which can not displace H2 from acid is

a) Hg

b) Ba

c) Al

d) Pb

Ans: (a)

a) Hg

73) 3 Faraday of electricity is passed through electrolytes

containing Al3+, Na+ and Cu2+ ion. The amounts of

Al, Cu and Na liberated at the cathode will be in the

molar ratio of

a) 3:2:1

b) 1:2:3

c) 2:3:6

d) 6:3:2

Ans: (c)

c) 2:3:6

74) A cells A and B contain aqueous acidified ferrous

chloride and ferric chloride respectively. The weights of

iron deposited by the same quantity of electricity in the

cells A and B are in the ratio of

a) 1:1

b) 3:1

c) 2:1

d) 3:2

Ans: (d)

d) 3:2

75) The current liberates 112 ml H2 gas at STP in 965

seconds. The current passed in ampere is

a) 1

b) 0.5

c) 0.1

d) 2

Ans: (a)

a) 1

76) The ECE of metal is “ E ”. The amount of the metal

deposited by the passage of 500 mA current through

the solution for 4 minutes will be

a) 2000E g.

b) 1200E g.

c) 120E g.

d) 2E g.

Ans: (a)

c) 120E g.

77) In a compound “x” g. of the metal combines with 35.5 g.

of chlorine. The weight of the metal liberated by the

passage of “y” coulomb of electricity through the

solution of the compound will be

a) b)

c) d)

Ans: (d)

g96500

xy .xyg

.y

96500g g

x

96500yg

x

96500y

Ans: (b)

It 60

96500w60It

96500w

78) “W” g. of a metal is deposited by a current o “I” ampere

for “t” minutes. The equivalent weight of the metal is

a) b)

c) d) 60WIt96500It

IT60

w

79) The standard EMF of a Daniell’s cell is 1.10 V. The

EMF of the cell at 250 c, when 0.1 M Cu2+ and 0.1 M

Zn2+ solutions are used, is

a) 1.10 V

b) – 1.10 V

c) 0.110 V

d) – 0.110 V

Ans: (a)

a) 1.10 V

80) The charge, in Faraday on 0.25 mole of electron is

a) b)

c) d)

Ans: (b)

F2

F

4

F 96500F4

F

81) Zn displaces silver from AgNO3 Solution, because

a) Zn is higher up in EMF series than Ag

b) Reduction potential of Zn is more than that of Ag

c) Zn reacts with AgNO3 Solution.

d) Oxidation potential of Zn is more than that of Ag

Ans: (d)

d) Oxidation potential of Zn is more than that of Ag

82) The Pt. foil in a hydrogen electrode is coated with

platinum black because the latter

a) increases its surface area and minimises

polarisation.

b) is a good conductor.

c) prevents the electrode from damage.

d) maintains better electrical contact.

Ans: (a)

a) Increases its surface area and minimises

polarisation.

83) The number of equivalents of Mn+ ions liberated by the

passage of n Faraday of charge through the solution of

Mn+ is

a) b)

c) d)

Ans: (b)

F n

n

1F

n

n

84) Anode is an electrode at which

a) electrons flow out of an electrolyte.

b) electrons flow into the electrolyte.

c) reduction takes places.

d) cations are converted to atoms.

Ans: (a)

a) electrons flow out of an electrolyte.

85) The EMF of an electrochemical cell must be measured

by a null method to avoid

a) heat generation

b) corrosion at the electrodes

c) changes in electrolyte concentration

d) the stoppage of cell reaction

Ans: (c)

c) changes in electrolyte concentration

86) Coulomb is a unit of

a) current

b) energy

c) work

d) charge

Ans: (d)

d) charge

87) Zinc displaces copper from the solution of the latter’s

salt because

a) atomic number of Zinc is more than that of copper

b) Zinc has more positive standard reduction

potential than copper.

c) Zinc has more positive standard reduction

potential than copper.

d) Zinc salt is more soluble in water than copper salt

Ans: (d)

d) Zinc salt is more soluble in water than copper salt

88) During electrolysis of water the volume of O2 liberated

is 2.24 dm3. The volume of hydrogen liberated, under

same conditions, will be

a) 2.24 dm3

b) 1.12 dm3

c) 4.48 dm3

d) 0.56 dm3

Ans: (c)

c) 4.48 dm3

89) The element which can displace lithium from the

solution is

a) Mg

b) Zn

c) H2

d) None of these

Ans: (d)

d) None of these

90) The EMF of the cell can not be measured accurately by

a voltmeter because,

a) there are concentration changes during

measurement

b) voltmeters are not very sensitive.

c) the voltmeter changes the cell reaction.

d) cations are converted to atoms.

Ans: (a)

a) there are concentration changes during

measurement

91) During the electrolysis of aqueous sodium chloride the

product obtained at the cathode is

a) sodium metal

b) chlorine

c) oxygen

d) hydrogen

Ans: (d)

d) hydrogen

92) A current of 5 ampere was passed through SnCl2

solution for 10 min and a current of 10 ampere through

a solution of SnCl4 for 5 min. The amount of tin

deposited in the 1st and 2nd case are x g and y g.

respectively, then

a) x = y

b) 2x = y

c) 2x = 3y

d) x = 2y

Ans: (d)

d) x = 2y

93) In the solution of an electrolyte the current is carried by

a) electrons

b) cations and anions

c) molecules

d) atoms

Ans: (a)

a) electrons

94) Which of the following statements is correct ?

a) During electrolytic dissolution, the number of

cations and anions obtained are always equal.

b) The electrolyte dissociation leads to reduction in

number of particles in the solution.

c) The cations and anions do not reunite to give

back neutral molecules.

d) The number of positive and negative ions are

equivalent

Ans: (d)

d) The number of positive and negative ions are

equivalent

95) Some statement are given below

A) Electrolysis is a non-spontaneous redox reaction.

B) ECE of an ion is its weight liberated by one Faraday of

electricity.

C) One device to convert electrical energy to chemical

energy is called Voltaic cell.

D) If the solution pressure of the metal is greater than the

osmotic pressure of cations, the metal electrode

becomes negatively charged.

Among the above

a) Only B is false

b) only C is false

c) B,C and D are false

d) B and C are false

Ans: (d)

d) B and C are false

96) The standard potential of an electrode is its potential

when the concentration of the salt solution is

a) 1 M at 25 K

b) 1 N at 25 K

c) 1 N at 298 K

d) 1 M at 298 K

Ans: (d)

d) 1 M at 298 K

Ans: (a)

97) For the cell reaction,

Cd(s) + 2 Ag+ (0.5 M) Cd2+(0.25M) +2Ag (s)

a) b)

c) d)

V 1.20 V298

303X20.1

V303

298X20.1 V)]

298

303x0591.0(20.1[

V 1.20

98) Faradays laws of electrolysis are related to the

a) atomic number of the cation.

b) atomic no of the anion.

c) equivalent mass of the electrolyte.

d) speed of the cation

Ans: (c)

c) equivalent mass of the electrolyte.

99) When a lead storage battery is discharged

a) SO2

b) lead sulphate is consumed

c) lead is formed.

d) sulphuric acid is consumed

Ans: (d)

d) sulphuric acid is consumed

100) If , I = current in ampere, t = time in seconds, Q =

charge passing in coulomb, then which of the

following expressions is correct ?

a) I = Qt

b) I = Q / t

c) I = 1 / Qt

d) I = t / Q

Ans: (b)

b) I = Q / t

101) In an electrolytic cell, which of the following is NOT

true?

a) Cathode is negative terminal.

b) Cathode is positive terminal.

c) Reduction occurs at cathode.

d) Electrons enter into cathode from the external

cell.

Ans: (b)

b) Cathode is positive terminal.

102) The density of Cu is x g cm-3 and its equivalent

weight is E. The quantity of electricity, in Faraday

needed to plate an area of 10 cm x 10 cm to a

thickness of 10-2 cm., using CuSO4 solution is

a) E / x

b) 96500 E / x

c) 96500x / E

d) x / E

Ans: (d)

d) x / E

103) When the lead accumulator is charged

a) sulphuric acid is formed

b) sulphuric acid is consumed

c) lead sulphuate is formed

d) lead is consumed

Ans: (a)

a) sulphuric acid is formed

104) In and electrolysis of aqueous solution of Na2SO4,

1.5 litre of oxygen was liberated at anode. The

volume of hydrogen, under similar conditions,

liberated at cathode would be

a) 0.75 litre

b) 1.5 litre

c) 3 litre

d) 12 litre

Ans: (c)

c) 3 litre

105) The quantity of the metal deposited at the cathode

during electrolysis depends on

a) Shape of cathode

b) concentration of electrolyte

c) only the quantity of charge passing through the

solution

d) the quantity of charge and vallancy of metal ion.

Ans: (d)

d) the quantity of charge and vallancy of metal ion.

106) In the electrolysis of acidulated water a total of 3 mole

of gases are evolved. The amount of water

decomposed would be

a) 3 mole

b) 2 mole

c) 6 mole

d) 4 mole

Ans: (b)

b) 2 mole

107) The atomic weight of a metal is 64. During

electrolysis of aqueous solution of its salt 3.2 g it are

deposited by the passage of 1/10 Faraday. The

valency of the metal ion is

a) 1

b) 2

c) 3

d) 4

Ans: (b)

b) 2

108) In acidic medium, MnO4- is converted to Mn2+. The

quantity of electricity in Faraday required to reduce 0.5

mole of MnO4- to Mn2+ would be

a) 2.5

b) 5

c) 1

d) 0.5

Ans: (a)

a) 2.5

109) The metal which can not be obtained by the

electrolysis of the aqueous solution of its salt is

a) Ag

b) Cr

c) Na

d) Cu

Ans: (c)

c) Na

110) The standard potentials for the following half-cell reactions are given against each:

Zn2+ (ag) +2e- Zn (s) ; - 0.763 V

2H+ (ag) + 2e- H2 (g) ; 0.000 V

Ni2+ (ag) + 2e- Ni (s) ; - 0.28 V

Fe3+ (ag) + e- Fe3+ (ag) ; 0.770 V

Among these, which is the strongest reducing agent ?

a) Fe3+ (ag) b) H2 (g) c) Ni (s) d) Zn (s)

Ans: (d)

d) Zn (s)

111) In the conventional representation of an

electrochemical cell, which of the following is correct ?

a) Right electrode is a positive terminal

b) Left electrode is cathode

c) Right electrode is anode

d) Left electrode is a positive terminal

Ans: (a)

a) Right electrode is a positive terminal

112) In the dry cell,

a) the graphite rod is negative terminal

b) the ammonia gas accumulates in the cell during

its working.

c) the Zn vessel is a negative terminal.

d) the cell reaction involves the complex formation of

Zn with MnO2

Ans: (c)

c) the Zn vessel is a negative terminal.

113) In the lead – storage cell

a) the cell reaction can not be reserved by any

method.

b) the EMF does not depend on the density of the

H2SO4 solution.

c) during charging the SO42- ions are liberated only

at anode

d) The spongly lead electrode behaves as –ve

terminal when the current is drawn from the cell.

Ans: (d)

d) The spongly lead electrode behaves as –ve

terminal when the current is drawn from the cell.

114) Some statements are given below

A) Reduction takes place at cathode in both, galvanic as

well as electrolytic cells.

B) Cathode is a negative terminal in both, galvanic and

electrolytic cells.

C) Anode is a negative terminal in an electrolytic cell but a

positive terminal in a galvanic cell.

D) Oxidation occurs at anode in a galvanic cell whereas

reduction occurs at anode in an electrolytic cell.

Amongst the above the false statements are

a) only A, B and C

b) only B, C and D

c) only B and D

d) all the four

Ans: (b)

b) only B, C and D

115) The S.O.P. of metals A and B are 0.40 V and - 0.77 V

respectively. These two metals are used as

electrodes in a cell. Which of the following statements

is correct for the cell ?

a) A serves as cathode

b) B serves as anode

c) Reduction occurs at B

d) E0 for the cell is 0.37 V

Ans: (c)

c) Reduction occurs at B

116) If E0 (Ca2+ / Ca) = -2.87 V and E0 (Sn2+ / Sn4+) = -0.15

V, the best reducing agent would be

a) Ca2+

b) Ca

c) Sn2+

d) Sn4+

Ans: (b)

b) Ca

117) The S.R.P. of A, B, C and D are – 0.40 V, -1.34 V,

0.80 V and 0.77 V respectively. Which of the

following will take place ?

a) D is displace A and C from their salt solutions.

b) A will displace B but not D from their salt

solutions.

c) B will displace all others from their salt solutions.

d) C will displace all others from their salt solutions.

Ans: (c)

c) B will displace all others from their salt solutions.

118) Some statements are given below

A) Cu metal can reduce Fe2+ in acidic medium.

B) Sodium metal can not be obtained by the electrolysis

of aqueous NaCl

C) In the Daniell cell electrons flow from Zn to Cu

electrode through the external circuit

D) Platinum wire in the calomel electrode is necessary

for the chemical reaction to take place.

Among the above, the false statement(s) is / are

a) only D

b) only B and C

c) only A and D

d) only A, B and D

Ans: (c)

c) only A and D

119) Which one of the following statements is false ?

a) The standard potential of hydrogen electrode is

zero at all conditions of temperature and

pressure.

b) The calomel electrode is reversible with chloride

ions

c) Reference electrode is that whose potential is

fixed under given conditions.

d) In a calomel electrode, as the concentration of Cl-

ions in the solutions increases, the reaction

potential decreasesAns: (a)

a) The standard potential of hydrogen electrode is

zero at all conditions of temperature and

pressure.

120) Some statements are given below

A) The EMF of a cell is an intensive property.

B) The cell EMF becomes half if the cell reaction is divided

by 2.

C) The external cell in the electrolysis experiment acts as a

galvanic cell.

D) The conventional value of zero potential of the standard

hydrogen half cell holds good at all temperatures.

Among the above

a) only A is true.

b) A and C are true.

c) A, B and D are false

d) only B is false.

Ans: (b)

b) A and C are true.

121) The equivalent weights of the element A, B and C are

in increasing order. Their weights deposited in

electrolytic cells by the same quantity of electricity are

x, y and w respectively. Then

a) x > y > w

b) x = y = w

c) x < y < w

d) x > y < w

Ans: (c)

c) x < y < w

122) The number of Faradays required to deposit one

mole atoms of M, when a solution of its M3+ ion is

electrolyzed, is

a) 3 / 2

b) 1 / 2

c) 3

d) 3 x 96500

Ans: (c)

c) 3

123) The no. of moles of Ag+, Cu2+ and Fe3+ ions

deposited by 2 Faradays of electricity would be in the

ratio of

a)1:2:3

b) 1:1:1

c) 3:2:1

d) 6:3:2

Ans: (d)

d) 6:3:2

124) In electrolysis the mass of ion discharged is not

proportional to

a) time

b) quantity of electricity

c) resistance of solution

d) Equivalent wt. of ion

Ans: (c)

c) resistance of solution

125) Among the following, the oxidation potential is

maximum in case of

a) NCE

b) DCE

c) SHE

d) SCE

Ans: (d)

d) SCE

126) A cell involves the reaction,

Sn(s) + 2Aq+ (aq) Sn2+ (aq) + 2Aq (s).

The EMF of the cell will increase by

a) increase in size of Ag electrode

b) increase in concentration of Sn2+ ions

c) decrease in concentration of Ag+ ions

d) increase in concentration of Ag+ ions

Ans: (d)

d) increase in concentration of Ag+ ions

127) In the salt bridge, KCl is used because

a) it is an electrolyte

b) it is a good conductor of electricity

c) The transport number of K+ and Cl- are nearly

equal

d) it is readily soluble in water

Ans: (c)

c) The transport number of K+ and Cl- are nearly

equal

128) During electrolysis of dilute H2SO4 solution the

amounts of substances liberated at cathode and

anode are in the ratio

a) 1:8

b) 8:1

c) 1:16

d) 16:1

Ans: (a)

a) 1:8

129) An ion is reduced to the element when it absorbs

6 x 1020 electrons. The number of equivalents of the

element produced will be

a) 0.10

b) 0.01

c) 0.001

d) 0.0001

Ans: (c)

c) 0.001

130) The standard EMF of the Daniell’s cell is 1.10 V. The

EMF of the cell when 0.1 M Cu2+ and 0.1M Zn2+

solutions are used will be

a) 1.10 V

b) 0.110 V

c) 1.110 V

d) 1.010 V

Ans: (a)

a) 1.10 V

131) The no. of electrons associated with one coulomb are

a) 6.02 X 1021

b) 6.24 X 1018

c) 6.24 X 1015

d) 6.02 X 1016

Ans: (b)

b) 6.24 X 1018

132) The electric charge needed for electrode – position of

1 gm equivalent of a substance is

a) one ampere per sec

b) 96500 coulomb per sec

c) one Faraday per sec

d) charge on one mole of electrons

Ans: (d)

d) charge on one mole of electrons

133) The charge in coulomb on Cu2+ ion is

a) 3.2 x 10-19

b) 2.3 x 10-12

c) 0.23 x 10-19

d) 1.6 x 10-19

Ans: (d)

d) 1.6 x 10-19

134) A metal having negative value for its reduction

potential, when dipped in the solution of its ions, has a

tendency to

a) go into the solution

b) be deposited form the solution

c) become positively charged

d) remain neutral

Ans: (a)

a) go into the solution

135) Using same quantity of electricity, the weight liberated

will be maximum in case of

a) Na

b) Mg

c) Al

d) Cl2

Ans: (d)

d) Cl2

136) In a Daniell’s cell, if the concentrations of Zn2+ and

Cu2+ ions are doubled, the EMF of the cell

a) is doubled

b) is reduced

c) remains same

d) becomes four times

Ans: (c)

c) remains same

137) Which of the following solutions can be safely stored

in a copper vessel

a) AuCl3

b) AgNO3

c) ZnSO4

d) all of these

Ans: (c)

c) ZnSO4

138) The no. of moles of electrons needed to deposit one

mole of Al from Al2(SO4)3 solution would be

a) 1

b) 2

c) 3

d) 4

Ans: (c)

c) 3

139) 1 x 10-2 g. atom of Ag can be oxidized to Ag+ by

using

a) 0.01 Faraday

b) 1 Faraday

c) 0.1 Faraday

d) 10 Faraday

Ans: (a)

a) 0.01 Faraday

140) The half-cell potential measures

a) the tendency of the electrode to gain or lose

electrode

b) the tendency of the cell reaction to occur

c) the current carried by the electrode

d) none of these

Ans: (b)

b) the tendency of the cell reaction to occur