REDOX REACTIONS AND ELECTROCHEMISTRY – 7

1) The electrochemical cell stops working after some time because 
a) The electrode potentials of both the electrodes become zero
b) The electrode potentials of both the electrodes become equal
c) One of the electrodes is eaten away
d) The reaction starts proceeding inthe opposite direction

2) Which of the following statement is incorrect for a galvanic cell ?
a) Reduction occurs at the cathode
b) Oxidation occurs at the anode
c) Electrons flow from the anode to the cathode
d) Oxidation and reduction occur at both electrodes. 

3) Which one of the following statements is correct ?
a) In an electrochemical cell , the free energy of the system decreases while in an electrolytic cell , it increases 
b) In an electrolytic cell ,the free energy of the system decreases while in an electrochemical cell it increases 
c) Free energy increases in both 
d) Free energy decreases in both

4) Which of the following statements is correct about a Zn-CuSOcell ?
a) The flow of electrons occurs from copper to zinc
b) Zinc is the cathode while Cu is the anode electrode
c) Zinc is the anode while Cu is the cathode electrode
d) All statements are correct.

5) Which of the following may not be present in galvanic cells ?
a) Electrolytes
b) Cathode
c) Anode
d) Salt bridge

6) Which one of the following reactions cannot be used to set up an electrochemical cell ?
a) 
b) 
c) 
d) 

7) Which one of the following statements is wrong about an electrochemical cell (ECC) and an electrolytic cell (ELC) ?
a) ECC produces electricity , ELC consumes electricity
b) ECC uses a salt bridge /porous pot,ELC does not
c) The anode of ECC is negative while the anode of ELC is positive
d) In both ECC and ELC , the redox reaction is spontaneous.

8) Cell reaction for the cell  is given by
a) 
b) 
c) 
d) 

9) The reduction potential of the two half cell reactions (occuring in an electrochemical cell ) are

. The feasible reaction will be
a) 
b) 
c) 
d) 

10) Which one of the following is not a function of a salt bridge ?
a) To allow the flow of cations from one solution to the other
b) To allow the flow of anions from one solution to the other
c) To allow the electrons to flow from one solution to the other 
d) To maintain electrical neutrality of the two solutions

11) KCl cannot be used as a salt bridge for the cell because
a) 
b) 
c) 
d) None of the above

12) In a salt bridge KCl is used because 
a) 
b) 
c) KCl is a strong electrolyte
d) KCl forms a good jelly with agar-agar.

13) If the salt bridge is removed suddenly from a working cell, the voltage
a) increases
b) decreases
c) drops to zero
d) may increase or decrease depending upon cell reaction

14) Electrolysis occurs on the passage of electricity through 
a) An aqueous solution of an electrolyte only
b) The melt of an electrolyte only
c) The aqueous solution or the melt of the electrolyte 
d) The aqueous solution or the melt of an electrolyte or a non -electrolyte

15) Electrolysis involves oxidation and reduction respectively at
a) The anode and cathode
b) The cathode and anode
c) both the electrodes
d) None of the above

16) Which of the substances , Na , Hg, S, Pt and graphite can be used as electrodes in electrolytic cells having aqueous solutions ?
a) Hg, Pt and graphite
b) Na , S and Hg
c) Pt and graphite only
d) Na and S only

17) In the electroplating of silver over an article made of iron, the electrolyte generally used is
a) 
b) 
c) 
d) 

18) According to  first law of electrolysis , the mass(m) of iron liberated is equal to
a) ZC/F
b) ZC
c) ZCt
d) 

19) On passing C ampere of electricity through an electrolyte solution for t seconds , m gram metal deposits on cathode .The eq.wt. of the metal is
a) 
b) 
c) 
d) 

20) When the quantity of electricity passed is one Faraday then the mass deposited at the electrode is equal to
a) One gm atomic weight
b) One gm equivalent weight
c) Electrochemical equivalent
d) None of the above

21) If the same quantity of current is passed through the two electrolytic solutions connected in series then the amount of product liberated at the electrode are in the ratio of their 
a) Densities
b) Electrochemical equivalents
c) Atomic masses
d) Atomic numbers

22) When the same quantity of electricity is passed, the electrochemical equivalents of the two metals liberated at the electrodes have the same ratio as that of their 
a) Atomic masses
b) Molecular masses
c) Equivalent masses
d) Any of the three

23) The electrochemical equivalent of a substance is equal to the weight of that substance deposited on the electrode by the passage of a current of 
a) One ampere for one second
b) One ampere for one minute
c) One ampere for one hour
d) 0.1 ampere for 100 seconds

24) Which one is not correct ?  law holds 
a) At all pressures 
b) Only at 298 K
c) In all concentrations
d) In different solvents

25) An apparatus used for the measurement of quantity of electricity is known as a 
a) Calorimeter
b) Cathetometer
c) Coulometer
d) Colorimeter

26) The weight of an ion deposited on an electrode depends
a) Only upon the strength of the current passed
b) Only upon the time for which the current is passed
c) Upon the quantity of electricity passed 
d) Upon the voltage of the battery

27) In the electrolysis of a fused salt, the weight of the ion deposited on the electrode will not depend on the
a) Temperature of the bath
b) Current intensity
c) Electrochemical equivalent of the ions
d) Time for electrolysis

28) The charge on one monovalent ion is
a) 96500 Faraday
b) 1 Faraday
c) 
d) 1 coulomb

29) The total charge on one mole of a monovalent ion is equal to 
a) 
b) 
c) 
d) None of the above

30) One coulomb is equal to 
a) 96500 Faraday
b) 
c) Charge on one electron
d) None of the above

31) The unit of Faraday is
a) Amperes
b) C
c) 
d) 

32) The unit of electrochemical equivalent is
a) gram / ampere
b) gram / coulomb
c) gram – ampere
d) coulomb / gram

33) The quantity of electricity needed to liberate one gram equivalent of an element is
a) 1 ampere
b) 96500 amperes
c) 96500 coulombs
d) 96500 faradays

34) If three faradays of electricity is passed through solutions of AgNO3 ,CuSOand AuCl3 , the molar ratio of the cations deposited at the cathodes will be 
a) 1:1:1
b) 1:2:3
c) 3:2:1
d) 6:3:2

35) On electrolysis, one mole of aluminium atoms will be deposited by
a) One mole of electrons
b) Two moles of electrons
c) Three moles of electrons
d) Four moles of electrons

36) In which one of the following will one Faraday of electricity liberate 1/2 gram atom of the metal ?
a) 
b) 
c) 
d) NaCl 

37) When an aqueous solution of H2SO4 is electrolysed, the ion discharged at the anode is 
a) 
b) 
c) 
d) 

38) On electrolysing a solution of dilute H2SO4 between platinum electrodes, the gas evolved at the anode is 
a) 
b) 
c) 
d) 

39) During the electrolysis of fused NaCl, which reaction occurs at the anode?
a) Chloride ions are oxidised
b) Chloride ions are reduced 
c) Sodium ions are oxidised
d) Sodium ions are reduced

40) Which of the following cell is a secondary cell?
a) Mercury cell
b) Ni-Cd cell
c) Dry cell
d) Fuel cell

41) Which of the following material is not present in dry cells?
a) 
b) 
c) 
d) KCl

42) Which of the following material is not present in a mercury cell ?
a) HgO
b) KOH
c) Zinc
d) 

43) The approximate voltage of a dry cell is
a) 2V
b) 1V
c) 6V
d) 1.5V

44) Which cell has a constant voltage for a longer period ?
a) Leclanche cell
b) Electrolytic cell
c) Mercury cell
d) Daniell cell

45) The depolariser used in a dry cell is
a) 
b) 
c) Carbon
d) 

46) When a lead storage battery is charged, it acts as
a) a primary cell
b) an electrolytic cell
c) a galvanic cell
d) a concentration cell

47) The reaction occurring at the anode during the recharging of a lead storage battery is
a) 
b) 
c) 
d) 

48) The reaction occurring at the anode during discharge of a lead storage battery is
a) 
b) 
c) 
d) 

49) The device used to convert the chemical energy of H2 gas into electrical energy is called a
a) Daniell cell
b) Electrolytic cell
c) Fuel cell
d) Storage cell

50) The source of electrical energy on the Appollo moon flights was
a) Lead storage batteries
b) A generator set
c) Fuel cells
d) Ni – Cd cells

51) In an H2-O2 fuel cell the reaction occuring at the cathode is
a) 
b) 
c) 
d) 

52) The thermodynamic efficiency of a fuel cell is given by
a) 
b) 
c) 
d) nFE

53) @ The reaction occurring at the anode in a Solvang cell is 
a) 
b) 
c) 
d) 

54) Chemically, rust is
a) 
b) 
c) 
d) 

55) According to the electrochemical theory of corrosion, the metal undergoing corrosion acts as
a) the anode
b) the cathode
c) neither anode nor cathode
d) either anode or cathode depending upon its standard reduction potential

56) In which of the following will the corrosion of iron be most rapid?
a) in pure water
b) in pure oxygen
c) in air and moisture
d) in air and saline water

57) Galvanised iron sheets are coated with
a) Nickel
b) Chromium
c) Copper
d) Zinc

58) Zinc is used to protect iron from rusting because
a) 
b) 
c) Zinc does not melt easily.
d) Zinc is cheap.

59) A metal is left exposed to the atmosphere for some time. It gets coated with green carbonate. The metal must be 
a) silver
b) copper
c) iron
d) zinc

60) The ionization constant of a weak electrolyte is 25 x 10-6 while the equivalent conductance of its 0.01 M solution is 19.6 S cm2 eq-1. The equivalent conductance of the electrolyte at infinite dilution (in S cm2 eq-1) will be
a) 250
b) 196
c) 392
d) 384

61) The molar ionic conductances at infinite dilution of Mg2+ and Cl are 106.1 and 76.3 ohm-1 cm2 mol-1 respectively. The molar conductance of a solution of MgCl2 at infinite dilution will be
a) 
b) 
c) 
d) 

62) An electrolytic cell contains a solution of Ag2SO4 and has platinum electrodes. A current is passed until 1.6 gm of O2 has been liberated at the anode. The amount of silver deposited at the cathode would be
a) 107.88 gm
b) 1.6 gm
c) 0.8 gm
d) 21.60 gm

63) What weight of copper will be deposited by passing 2 faradays of electricity through a cupric salt (at. wt of Cu = 63.5) ?
a) 2.0 g
b) 3.175 g
c) 63.5 g
d) 127.0 g

64) How many c.c. of oxygen will be liberated at STP by 2 ampere current flowing for 3 minutes and 13 seconds through acidulated water ?
a) 11.2 c.c.
b) 33.6 c.c.
c) 44.8 c.c.
d) 22.4 c.c.

65) 2.5 faraday of electricity is passed through a solution of CuSO4. The number of gram equivalents of copper deposited on the cathode will be
a) 1
b) 2
c) 2.5
d) 1.25

66) On passing 1 Faraday of electricity through the electrolytic cells containing Ag+, Ni2+, Cr3+ ions solution, the deposited Ag (At. wt = 108), Ni (At. wt = 59) and Cr (At. wt = 52) are
a) Ag – 108 gm Ni – 29.5 gm Cr – 17.3 gm
b) Ag – 108 gm Ni – 59.0 gm Cr – 52.0 gm
c) Ag – 108 gm Ni – 108 gm Cr – 108 gm
d) Ag – 108 gm Ni – 117.5 gm Cr – 166.0 gm

67) A certain quantity of electricity is passed through an aqueous solution of AgNO3 and cupric salt solution connected in series. The amount of Ag deposited is 1.08 gm, then the amount of copper deposited is (At. wt. Cu = 63.5 ; Ag = 108).
a) 0.6454 g
b) 6.354 g
c) 0.3177 g
d) 3.177 g

68) The electrochemical equivalent of silver is 0.001118 g . When an electric current of 0.5 ampere is passed through an aqueous silver nitrate solution for 200 seconds, the amount of silver deposited is
a) 1.118 g
b) 0.1118 g
c) 5.590 g
d) 0.5590 g

69) The quantity of electricity needed to liberate 0.5 gram equivalent of an element is
a) 48250 faraday
b) 48250 coulomb
c) 19300 faraday
d) 19300 coulomb

70) On the electrolysis of acidified water, if the volume of hydrogen liberated is 5.6 cm3, then the volume of oxygen liberated is equal to
a) 
b) 
c) 
d) 

71) How many coulombs of electricity are consumed when 100 mA current is passed through a solution of AgNO3 for half an hour during an electrolysis experiment ?
a) 108
b) 180
c) 1800
d) 18000

72) The standard emf of a Danieli cell is 1.1 volt. The maximum electrical work obtained from the Danieli cell is
a) 212.3KJ
b) 175.4KJ
c) 106.15KJ
d) 53.07KJ

73) The standard electrode potentials of the two half cells are given below:

Ni2++2e=Ni;E0=-0.25 volt

Zn2++2e=Ni;E0=-0.77 volt

The voltage of a spontaneous cell formed by combining the two half cells would be
a) -1.02Volt
b) +0.52Volt
c) +1.02 Volt
d) -0.52Volt

74) @ The voltage of a spontaneous cell whose half cells are given below is


a) -2.03V
b) 1.36V
c) 2.71V
d) 2.03V

75) E0 for the cell, Zn|Zn2+ (aq) || Cu2+ (aq)| Cu is 1.10 V at 250C. The equilibrium constant for the cell reaction.  is of the order of
a) 
b) 
c) 
d) 

76) For a reaction  Kc has been found to be 1012. The E0cell is:
a) 0.354V
b) 0.708V
c) 0.0098V
d) 1.36V

77) The equilibrium constant (K) for the reaction Cu(s)+2Ag+(ag) Cu2+(ag)+2Ag(s) will be: [Given E0cell=0.46V] 
a) 
b) 
c) 
d) 

78) @ Calculate the standard free energy change for the reaction, 2Ag+2Hà H2+2Ag+
a) +212.3KJ
b) +308.8KJ
c) +154.4KJ
d) -308.8KJ

79) Which one of the following is not a property of a colloidal sol?
a) The colloidal particles in them do not settle down
b) They can pass through an animal membrane
c) The particles can be seen under a microscope
d) Although colloidal particles carry charge, yet the colloidal sol on the whole is electrically neutral

80) The equivalent weight of an acid is equal to 
a) 
b) 
c) Molecular weight / basicity
d) Molecular weight / acidity

81) In the following groups :
—OAc(l),
— OMe(ll),
—OSO2Me (III),
— OSO2CF3 (IV)
the order of leaving group ability is

a) I > II >lll >IV
b) IV>lll>l> II
c) lll> II>I>IV
d) ll> lll> IV > I.

82) E° values for the couples Cr3+/Cr2+ andMn3+/Mn2+ are —0.41 and +1.51 volts respectively.
These values suggest that

a) 
b) 
c) 
d) 

83) The electrode potential of a hydrogen electrode in neutral solution at 298 K is
a) – 0. 41 V
b) Zero
c) – 0.49 V
d) + 0. 41 V

84) The strongest Lewis base is
a) -3

b) -3

c) -2

d) F

85) An example of a Lewis acid is
a) Ca O
b) CH3NH2

c) SO3

d) None of these

86) A compound having the formula NH2CH2 COOH may behave
a) Only as an acid
b) Only as a base
c) Both as an acid and base
d) Neither acid nor base

87) The number of electrons passing per second through a cross section of a copper wire carrying 10-16 amperes is
a) 625
b) 60
c) 6000
d) 6

88) How long will it take for a current of 3 amperes to decompose 36 gm of water?
a) 36 hours approx
b) 18 hours approx
c) 9 hours approx
d) 4.5 hours approx

89) The charge required to liberate 11. 5 g sodium from fused sodium chloride is
a) 0.5 Faraday
b) 1.0 Faraday
c) 1.5 Faraday
d) 96500 coulomb

90) 0. 1978 gm of copper is deposited by a current of 0.2 amp in 50 minutes. What is the electro chemical equivalent of copper?
a) 0. 0003296
b) 0. 003296
c) 0. 3296
d) 3. 296

91) Two electrolytic cells, one containing acidified ferrous chloride and another acidified ferric chloride and connected in series. The ratio of iron deposited at the cathodes in the two cells will be
a) 3 : 1
b) 2 : 1
c) 1 : 1
d) 3 : 2

92) How many cm3 of hydrogen at STP will be liberated by a current of 5 amp flowing for 25 minutes through aciduated water?

a) 8. 736 cm3

b) 870. 4 cm3

c) 87. 36 cm3

d) None of these

93) To deposit 6.23 x 1023 molecules of chlorine we need 
a) 2 moles of electrons
b) 96500 amperes
c) 6. 02 x 1023 coulombs
d) 1 mole of electrons

94) The compound that cannot be used in a salt bridge is
a) Sucrose
b) Mg SO4

c) K cl

d) NaCl

95) The e. m. f of the cell Ag / Ag + ( 0.1 M ) 11 Ag+ ( 1 M )  / Ag at 298 K is
a) 0.0059 V
b) 0.059 V
c) 5.9 V
d) 0.59 V

96) The electrode potential of a gas electrode depends upon the
a) Concentration of chloride ions
b) Concentration of hydrogen ion
c) Concentration of KCl solution
d) None of these

97) If three electrons are lost by a metal atom to get  M3+,  its final oxidation number would be
a) 0
b) +6
c) +2
d) +3

98) Oxygen has an oxidation state of +2 in the compound
a) H2O2

b) CO2

c) H2O

d) F2O

99) What is the oxidation number of Manganese in K2MnO4?
a) 2
b) 4
c) 6
d) 7

100) The oxidation number of nitrogen in NH2OH is
a) +1
b) -1
c) -3
d) -4


Answer :

Related Posts
Leave a reply
What is the capital of Egypt ?