REDOX REACTIONS AND ELECTROCHEMISTRY – 6

1) Given that E0Zn2+/Zn=-0.763V and E0Cd2+/Cd=-0.403V, the emf of the cell Zn|Zn2+ || Cd2+ |Cd
(a=0.004) (a=0.2) will be given by
a) E=-0.36+(0.059/2)log(0.004/2)
b) E=+0.36+(0.059/2)log(0.004/2)
c) E=-0.36+(0.059/2)log(0.2/0.004)
d) E+0.36+(0.059/2)log(0.2/0.004)

2) Which one of the following represents a standard hydrogen electrode correctly ?
a)
b)
c)
d)

3) The primary reference electrode for the measurement of electrode potential is
a) SHE (Standard hydrogen electrode )
b) Normal calomel electrode
c) Glass electrode
d) None of these

4) The electrode potential of the calomel electrode, used as a reference electrode,
a) Is taken as zero always
b) Is taken as zero if concentration of KCl solution is 1 M
c) Can be zero , negative or positive
d) Depends upon the concentration of the KCl solution used

5) The normal hydrogen electrode (N.H.E) has been assigned a potential of
a) 0 volt
b) 1 volt
c) 10 volt
d) 100 volt

6) The standard potential of Cu | Cu2+ electrode =-0.337 V . It corresponds to the reaction
a)
b)
c)
d) None of the above

7) Arrange Mg, K, Ba, Ca in the order of their decreasing standard reduction potentials
a) K, Ba, Mg,Ca
b) Ba, Ca, K, Mg
c) Ca, Mg ,K, Ba
d) Mg, Ca, Ba, K

8) The correct electrochemical series can be obtained from K, Na, Ca, Al, Mg, Zn, Fe , Pb, H, Cu, and Ag by interchanging
a) Only Al and Mg
b) Only Na and Ca
c) Both the above
d) None

9) The stronger the oxidising agent, the greater is the
a) Reduction potential
b) Oxidation potential
c) Ionic behaviour
d) None of the above

10) The position of some metals in the electrochemical series in decreasing electropositive character is given below

Mg> Al > Zn > Cu > Ag

What will happen if a copper spoon is used to stir a solution of aluminium nitrate ?
a) The spoon will get coated with aluminium
b) An alloy of copper and aluminium is formed
c) The solution becomes blue
d) There is no reaction

11) For a redox reaction to be spontaneous , the e.m.f should be
a) Negative
b) Positive
c) Zero
d) Very high

12) For some reaction the standard reduction potentials are given below

Which one of the following is most easily oxidised ?
a) Zn
b) Cu
c) Fe
d) Ag

13) The values of the standard oxidation potentials for some reactions are given below:

(a )

(b)

(c)

(d)

Which one of the following is most easily reduced ?
a)
b)
c)
d)

14) To one molar solutions of NaCl, CdCl2 , ZnCl2 and PbCl2, tin metal is added .Which of the following is true? Given


a)
b)
c)
d)

15) Out of Cu, Ag, Fe and Zn, the metal which can displace all others from their salt solution is
a) Ag
b) Cu
c) Zn
d) Fe

16) Iron displaces copper from the solution of its salt because
a)
b) The standard reduction potential of copper is less than that of iron
c) The standard reduction potential of iron is less than that of copper
d) The iron salt is more soluble in water than copper salt

17) Using the standard electrode potential values given below , decide which of the statements I,II, III, IV are correct.Choose the right answer from (a) ,(b) ,(c) and (d)

  1. Cu can displace Fe from FeSO4 solution
  2. Fe can displace Cu from CuSO4 solution
  3. Ag can displace Cu from CuSO4 solution
  4. Fe can displace Ag from AgNO3 solution

a) I and II
b) II and III
c) II and IV
d) I and IV

18) Which of the following metals will not react with a solution of CuSO4 ?
a) Fe
b) Zn
c) Mg
d) Ag

19) The standard reduction potentials of Ag,Cu and Zn are 0.80 V,0.34 V and -0.76 V respectively.Which of the following can be stored?
a)
b)
c)
d)

20) CuSO4 is not stored in aluminium bottles because
a) Cu gets oxidised
b) Cu gets reduced
c) Al gets reduced
d)

21) Which of the following will turn blue when placed in a copper vessel ?
a)
b)
c) aq.ZnSO4
d)

22) The oxidation potential of Mg and Al is +2.37 and +1.66 volts respectively.The Mg in chemical reactions
a) Will be replaced by Al
b) Will replace Al
c) Will not be able to replace Al
d) None of these

23) If a strip of copper metal is placed in a solution of ferrous sulphate
a) Copper will precipitate out
b) Iron will precipitate out
c) Copper and iron both will be dissolved
d) No reaction will take place

24) The standard electrode potentials of four elements A, B, C and D are -3.65, -1.68 , -0.80 and +0.86. The highest chemical activity will be exhibited by
a) A
b) B
c) C
d) D

25) To a mixture containing pieces of zinc , copper and silver, 1 M H2SO4 was added. H2 gas was found to be evolved. Which of the metal / metals do you think has/have reacted ?Given
a) All the metals
b) Only Zn
c) Both Zn and Cu
d) Only Ag

26) 

The cell represented above will have an e.m.f
a) Positive
b) Negative
c) Zero
d) Cannot be predicted

27) In a simple electrochemical cell which is in the standard state, half cell reactions with their appropriate oxidation potentials are

Which of the following reactions takes place ?
a)
b)
c)
d)

28) I2 and Br2 are added to a solution containing 1 M each of and ions.Which of the following reactions will take place (given standard reduction potentials of I2 and Br2 are 0.53 and 1.09 volts respectively.) ?
a) Iodine will reduce bromide ions
b) Bromine will reduce iodide ions
c) Iodide ions will reduce bromine
d) Bromide ions will reduce iodine.

29) The Nernst equation showing the dependence of the electrode potential on concentration is
a)
b)
c)
d)

30) For the reaction   the Nernst equation for the EMF of the cell is
a)
b)
c)
d)

31) The electrode potential of a half cell depends upon the
a) Nature of the metal
b) Concentration of metal ions in solutions
c) Temperature
d) All

32) The reduction potential of an electrode
a) Increases with an increase in the concentration of the ions
b) Decreases with an increase in the concentration of the ions
c) Remains unaffected with an increase in the concentration of ions
d) Increases with an increase of temperature

33) The emf of the cell Tl | Tl+ (0.001 M) || Cu2+ (0.01M) | Cu is 0.83 V. The emf of this cell could be increased by
a)
b)
c)
d) None of the above

34) Two Daniell cells were set up, one with 1 M ZnSO4 and 1 M CuSO4, the other with 2M ZnSO4 and 2M CuSO4 .Their are E1 and E2 respectively. Then
a)
b)
c)
d)

35) The Nernst equation gives the effect of
a) Temperature on EMF
b) Concentration on EMF
c) Pressure of the gas (if any ) on EMF
d) All the three above

36) When the cell reaction attains a state of equillibrium , the EMF of the cell is
a) Zero
b) Positive
c) Negative
d) Not definite

37) The EMF of a cell is related to the equillibrium constant of the cell reaction as
a)
b)
c)
d)

38) The correct relationship between the standard free energy change and the emf of a cell is
a)
b)
c)
d)

39) The standard free energy change is related to the equillibrium constant as
a) G0=RT In K
b) G0=RT log K
c) G0=2.303 RT log K
d) G0=(RT log K)/2.303

40) The EMF of a chemical cell is positive when the free energy change of reaction
a) > 0
b) < 0
c) =0
d) has a very large value

41) The standard reduction potentials E0 for the half reactions are as

Zn Zn2+ + 2e;E0=0.76v

Fe Fe2+ + 2e;E0=0.41v
a) -0.35 V
b) 0.35V
c) 1.17V
d) -1.17V

42) A cell constructed by coupling a standard copper electrode and a standard magnesium electrode has an emf of 2.7 volts. If the standard reduction potential of the copper electrode is +0.34 volt, that of the magnesium electrode is
a) +3.04 volts
b) -3.04 volts
c) -2.36 volts
d) +2.36 volts

43) What is the emf of the cell, given

The cell has electrodes A and B in their respective electrolytes
a) +0.07V
b) -0.07V
c) +0.77V
d) -0.77V

44) Electrode potential of is -0.76 V and that of Cu2+/Cu is +0.34V. The emf of the cell constructed between these two electrodes is
a) 1.10V
b) 0.42V
c) -1.1V
d) -0.42V

45) The standard electrode potentials of Zn2+/Zn and Ag+/Ag are -0.763V and +0.799V respectively. The standard potential of the cell is
a) 1.562V
b) 0.036V
c) -1.562V
d) 0.799V

46) Given electrode potentials , E0cell for reaction
a)
b)
c) 0.771- 0.536=0.235 volt
d) 0.536 – 0.771=-0.235 volt

47) @ The standard electrode potentials (E0) for OCl/Cl and Cl/0.5Cl2 respectively are 0.94V and -1.36V. The E0 value for OCl/0.5Cl2 will be
a) -0.42 V
b) -2.20V
c) 0.52V
d) 1.04V

48) The standard reduction potential for Fe2+/Fe and Sn2+/Sn electrodes are -0.44 and -0.14 volt respectively. For the cell reaction the standard emf is
a) +0.30V
b) -0.58V
c) +0.58V
d) -0.30V

49) The emf of the cell Ni/Ni2+ (1.0M)||Au3+(1.0M)/Au is [E0 for Ni2+/Ni=-0.25V;E0 for Au3+/Au=1.5v] is
a) +1.25V
b) +1.75V
c) -1.25V
d) -1.75V

50) The standard reduction potentials of Mg, Zn,Ni, H2, Cu and Ag are -2.37,-0.76,-0.25,0.0,0.34 and 0.80 volt respectively. Which one of the following cells has the minimum voltage?
a)
b)
c)
d)

51) The EMF of the cell  Ni|Ni2+||Cu2+|Cu is 0.59 Volt. The standard electrode potential (reduction potential) of the copper electrode is 0.34 volt. The standard electrode potential of the nickel electrode will be
a) 0.25Volt
b) -0.25Volt
c) 0.93Volt
d) -0.93Volt

52) The e.m.f of the cell involving the reaction 2Ag+(aq)+H2(g) 2Ag(s)+2H+(aq) is 0.80V. The standard oxidation potential of the silver electrode is
a) 0.80V
b) -0.80V
c) 0.40V
d) 0.20V

53) The of the following cells are Cu|Cu2+(1M)||Ag+(1M)|Ag,E0=0.46V     Zn|Zn2+(1M)||Cu2+(1M)|Cu,E0=1.10V    The EMF of the cell Zn|Zn2+||Ag+(1M)|Ag will be
a) 1.56V
b) 0.64V
c) -1.56V
d) 2.02V

54) The half cell reactions of the cell used in hearing aids are    

E0 of the cell will be
a) 0.42V
b) 1.1V
c) 0.84V
d) 2.2V

55) The standard reduction potential of Pb and Zn electrodes are -0.126 and-0.763 volts respectively. The emf of the cell; Zn/Zn2+ (0.1M) || Pb2+ (1M) / Pb is
a) 0.637V
b) < 0.637V
c) > 0.637V
d) 0.889V

56) The standard EMF for the cell reaction, is 1.1 volt at 250 C. The EMF for the cell reaction, when 0.1M Cu2+ and 0.1MZn2+ solutions are used, at 250C is
a) 1.10V
b) 0.10V
c) -1.10V
d) -0.110V

57) If the pressure of hydrogen gas is increased from 1atm to 100 atm, keeping the hydrogen ion concentration constant at 1M, the voltage of the hydrogen half-cell at 250 C will be
a) 0.059V
b) -0.059V
c) 0.295V
d) 0.118V

58) The EMF of the cell Mg|Mg2+ (0.01M)|| Sn2+ (0.1M)|Sn at 298K is (given E0 Mg2+ ,Mg=-2.34V, E0 Sn2+ ,Sn=-0.14V)
a) 2.17V
b) 2.23V
c) 2.51V
d) 2.45V

59) The potential of the cell containing two hydrogen electrodes as represented below is
Pt, H2(g)|H+(10-6M)||H+(10-4M)| H2 (g), Pt at 298K

a) -0.118V
b) -0.0591V
c) 0.118V
d) 0.0591V

60) The potential of hydrogen electrode at pH = 10 and 250C is
a) 0.59Volt
b) zero volt
c) -0.59 volt
d) -0.059volt

61) In the cell Zn|Zn2+(C1)||Cu2+(C2)|Cu, Ecell -E0cell= 0.0591 V. The ratio C1/C2 at 298k will be
a) 2
b) 100
c) 1/100
d) 1

62) The solution of nickel sulphate in which a nickel rod is dipped is diluted 10 times. The potential of nickel
a) Decreases by 60mv
b) Increases by 30v
c) Decreases by 30mv
d) Decreases by 60V

63) The emf of the cell H2(1atm)Pt | H+(a=x) || H+(a=1)| H2(1atm)Pt at 250C is 0.59V. The pH of the solution is
a) 1
b) 4
c) 7
d) 10

64) An electrolyte
a) has ions only when dissolved in water
b) gives ions only when electric current is passed
c) has ions even in the solid state
d) does not give complex ions in the solution

65) An electrolyte when dissolved in water dissociates into ions because
a) they are unstable
b) forces of attraction are quite weak
c) the forces of repulsion increase
d) the forces of electrostatic attraction are broken down by water

66) The conduction of electricity through metallic conductors is due to the movement of
a) metal atoms
b) electrons
c) ions
d) metallic kernals

67) The flow of electrons in an electrolyte is due to the movement of
a) electrons
b) protons
c) ions
d) molecules

68) The effect of temperature increase on conduction is as follows:
a) metallic conduction increases , electrolytic conduction decreases
b) electrolytic conduction increases , metallic conduction decreases
c) both metallic and electrolytic conduction decrease
d) both metallic and electrolytic conduction increase

69) Which one of the following will not conduct electricity ?
a) Crystalline NaCl
b)
c) Graphite
d) NaCl crystal having defects

70) The best conductor of electricity is a 1M solution of
a) Boric acid
b) Acetic acid
c) Sulphuric acid
d) Phosphoric acid

71) An electric current is passed through an aqueous solution of the following compounds. Which one will decompose ?
a) Urea
b) Glucose
c) Silver nitrate
d) Ethyl alcohol

72) The conductance of 0.1M HCl solution is greater than that of 0.1M NaCl .This is because
a) HCl is more ionized than NaCl
b) HCl is an acid whereas NaCl solution is neutral
c)
d) Interionic forces in HCl are weaker than those in NaCl

73) The addition of a polar solvent to a solid electrolyte results in
a) Polarisation
b) Association
c) Ionisation
d) Dissociation

74) The degree of ionisation increases
a) With increase in the concentration of the solution
b) On addition of excess of water to the solution
c) On decreasing the temperature of the solution
d) On stirring the solution vigorously

75) The theory of ionisation was put forward by
a) Ostwald
b) Arrhenius
c) Kohlraush
d) Lewis

76) Which has the maximum conductance ?
a) Copper
b) Iron
c) Silver
d) Teflon

77) Which has the minimum conductance ?
a) Silicon
b) Graphite
c) Sodium
d) Teflon

78) Conductivity stands for
a) Conductance
b) Specific Conductance
c) Equivalent Conductance
d) Molar Conductance

79) Which one of the following will have the highest conductivity ?
a)
b)
c)
d)

80) If the distance between the electrodes is 1 cm and the area of cross-section is 1 cm2 , then the conductance of the solution filling the above vessel is called
a) Conductivity
b) Conductance
c) Equivalent conductivity
d) Resistivity

81) The units of conductivity are
a) Ohm cm
b) Siemens (S)
c) S cm
d)

82) The units of equivalent conductance are
a)
b)
c)
d)

83) W -1m-1 is the unit of
a) Molar conductivitiy
b) Specific conductivity
c) Equivalent conductivity
d) Molar conductivity at infinite dilution

84) The units of cell constant are
a)
b)
c)
d)

85) The relationship between equivalent conductivity (), specific conductivity (K) and normality (X) of a solution is
a)
b)
c)
d)

86) The value of specific conductance is equal to the conductance of the solution when
a) The cell constant is zero
b) The cell constant is one
c) The electrodes are made of copper
d) The size of the vessel is large

87) The emf of a Daniell cell is 1.1 volt. If the value of a faraday is 96500 coulombs per mole, the change in free energy in KJ is
a) 212.30
b) -212.30
c) 106.15
d) -106.15

88) The cell constant is the product of resistance and
a) Conductance
b) Molar conductance
c) Specific conductance
d) Specific resistance

89) Which of the following solutions has the highest equivalent conductance ?
a) 0.01M NaCl
b) 0.050M NaCl
c) 0.005M NaCl
d) 0.02M NaCl

90) The equivalent conductance of KCl solution increases with dilution because the
a) Ionization of KCl increase with dilution
b) Inter-ionic forces of attraction decrease with dilution
c) products of hydrolysis of KCl are a strong acid and a strong base
d) Presence of KCl increases the ionisation of water

91) The increase in the value of the molar conductivity of acetic acid with dilution is due to the
a) decrease in inter-ionic forces
b) increase in the degree of ionisation
c) increase in self ionisation of water
d) none of these

92) What is the free energy change for the half reaction Given E0 Li+/Li= -3.0V, F=96500Cmol-1 and T=298K
a) 289.5KJ/mol
b) -289.5KJ/mol
c) 32.166 CV/mol
d) -289500CV/mol

93) At infinite dilution , the equivalent conductivity of an electrolyte is given by .The above statement has been given by
a) Ostwald
b) Hittorf
c) Kohlrausch
d) None of these

94) According to Kohlrausch law , the limiting value of molar conductivity of an electrolyte , A2B is
a)
b)
c)
d)

95) Which one of the following statements is wrong ?
a) K+ has different molar ionic conductivity at infinite dilution in KCl and KBr
b)
c)
d)

96) When a copper wire is immersed in silver nitrate solution, the solution becomes blue. This is due to the
a) Oxidation of copper
b) Oxidation of silver
c) Reduction of copper
d) Formation of a soluble complex having blue colour

97) When a zinc rod is suspended in copper sulphate solution
a) The temperature of the solution rises
b) The temperature of the solution falls
c) The temperature of the solution remains unchanged
d) Copper is deposited on the zinc rod thereby increasing its weight

98) Which one of the following statements is incorrect regarding an electrochemical cell ?
a) The electrode on which oxidation takes place is called the anode
b) The anode is a negative pole
c) The direction of current is same as that of the flow of electrons
d) The flow of current is partly due to the flow of ions

99) Which one of the following is different from others ?
a) Daniell cell
b) Voltaic cell
c) Galvanic cell
d) Electrolytic cell

100) In an electrochemical cell
a) Kinetic energy changes into potential energy
b) Chemical energy changes into electrical energy
c) Potential energy changes into kinetic energy
d) Kinetic energy changes into chemical energy.


Answer :

 

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