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Electro Chemistry One Mark Questions with Answer

12th Standard

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Chemistry

Time : 00:30:00 Hrs
Total Marks : 25
    25 x 1 = 25
  1. The number of electrons that have a total charge of 9650 coulombs is_______.

    (a)

    6.22 ×1023

    (b)

    6.022 ×1024

    (c)

    6.022 ×1022

    (d)

    6.022 ×10−34

  2. Consider the following half cell reactions.
    Mn2+ + 2e- ➝ Mn Eo = -1.18V
    Mn2+ ➝ Mn3+ + e- Eo = -1.51V
    The Eo for the reaction 3Mn2+➝ Mn + 2Mn3+, and the possibility of the forward reaction are respectively.

    (a)

    2.69V and spontaneous

    (b)

    -2.69 and non spontaneous

    (c)

    0.33V and Spontaneous

    (d)

    4.18V and non spontaneous

  3. The button cell used is watches function as follows
    Zn (s) + Ag2O (s) + H2O (l) ⇌ 2Ag (s) + Zn2+ (aq) + 2OH-(aq) the half cell potentials are Ag2O (s) + H2O (l) + 2e- → 2Ag (s) + 2OH- (aq) E= 34V and Zn (s) → Zn2+ (aq) + 2e E0 = 0.76V . The cell potential will be_______.

    (a)

    0.84V

    (b)

    1.34V

    (c)

    1.10V

    (d)

    0.42V

  4. The molar conductivity of a 0.5 mol dm-3 solution of AgNO3 with electrolytic conductivity of 5.76 ×10−3 S cm−1at 298 K is______.

    (a)

    2.88 S cm2mol-1

    (b)

    11.52 S cm2mol-1

    (c)

    0.086 S cm2mol-1

    (d)

    28.8 S cm2mol -1

  5. Electrolyte KCl KNO3 HCl NaOAC NaCl
    Λ-
    (Scm2 mol-1)
    149.9 145.0 426.2 91.0 126.5

    Calculate ΛoHoAC using appropriate molar conductances of the electrolytes listed above at infinite dilution in water at 25oC_______.

    (a)

    517.2

    (b)

    552.7

    (c)

    390.7

    (d)

    217.5

  6. Faraday constant is defined as_______.

    (a)

    charge carried by 1 electron

    (b)

    charge carried by one mole of electrons

    (c)

    charge required to deposit one mole of substance

    (d)

    charge carried by 6.22 ×1010 electrons

  7. How many faradays of electricity are required for the following reaction to occur MnO4-→ Mn2+

    (a)

    5F

    (b)

    3F

    (c)

    1F

    (d)

    7F

  8. A current strength of 3.86 A was passed through molten Calcium oxide for 41 minutes and 40 seconds. The mass of Calcium in grams deposited at the cathode is_______. (atomic mass of Ca is 40g / mol and 1F = 96500C).

    (a)

    4

    (b)

    2

    (c)

    8

    (d)

    6

  9. During electrolysis of molten sodium chloride, the time required to produce 0.1mole of chlorine gas using a current of 3A is _____.

    (a)

    55 minutes

    (b)

    107.2 minutes

    (c)

    220 minutes

    (d)

    330 minutes

  10. The number of electrons delivered at the cathode during electrolysis by a current of 1A in 60 seconds is ____. (charge of electron = 1.6 ×10−19C )

    (a)

    6.22 ×1023

    (b)

    6.022 ×1020

    (c)

    3.75 ×1020

    (d)

    7.48 ×1023

  11. Which of the following electrolytic solution has the least specific conductance?

    (a)

    2N

    (b)

    0.002N

    (c)

    0.02N

    (d)

    0.2N

  12. While charging lead storage battery _______.

    (a)

    PbSO4 on cathode is reduced to Pb

    (b)

    PbSO4 on anode is oxidised to PbO2

    (c)

    PbSO4 on anode is reduced to Pb

    (d)

    PbSO4 on cathode is oxidised to Pb

  13. Among the following cells
    I) Leclanche cell
    II) Nickel – Cadmium cell
    III) Lead storage battery
    IV) Mercury cell
    Primary cells are ____.

    (a)

    I and IV

    (b)

    I and III

    (c)

    III and IV

    (d)

    II and III

  14. Zinc can be coated on iron to produce galvanized iron but the reverse is not possible. It is because _______.

    (a)

    Zinc is lighter than iron

    (b)

    Zinc has lower melting point than iron

    (c)

    Zinc has lower negative electrode potential than iron

    (d)

    Zinc has higher negative electrode potential than iron

  15. Assertion: pure iron when heated in dry air is converted with a layer of rust.
    Reason: Rust has the composition Fe3 O4
    Codes:
    a) if both assertion and reason are true and reason is the correct explanation of assertion
    b) if both assertion and reason are true but reason is not the correct explanation of assertion
    c) assertion is true but reason is false
    d) both assertion and reason are false

    (a)

    if both assertion and reason are true and reason is the correct explanation of assertion

    (b)

    if both assertion and reason are true but reason is not the correct explanation of assertion

    (c)

    assertion is true but reason is false

    (d)

    both assertion and reason are false

  16. In H2-Ofuel cell the reaction occur at cathode is _______.

    (a)

    O2(g) + 2H2O(l) + 4e- ⟶ 4OH (aq)

    (b)

    H+(aq) + OH (aq) ⟶ H2O (l)

    (c)

    2H2 (g) + O2 (g) ⟶ 2H2O (g)

    (d)

    H+ + e- ⟶ 1/2 H2

  17. The equivalent conductance of M/36 solution of a weak monobasic acid is 6 mho cm2 equivalent-1 and at infinite dilution is 400 mho cm2 equivalent-1. The dissociation constant of this acid is ______.

    (a)

    1.25 x 10−6

    (b)

    6.25 x 10-6

    (c)

    1.25 x 10−4

    (d)

    6.25 x 10 -5

  18. A conductivity cell has been calibrated with a 0.01M, 1:1 electrolytic solution (specific conductance (k = 1.25 x 10-3cm-1) in the cell and the measured resistance was 800 Ω at 25oC. The cell constant is ______.

    (a)

    10−1 cm−1

    (b)

    101 cm−1

    (c)

    1 cm−1

    (d)

    5.7 x 10-12

  19. Conductivity of a saturated solution of a sparingly soluble salt AB (1:1 electrolyte) at 298K is 1.85 ×10−5 S m−1. Solubility product of the salt AB at 298K (Λom)AB = 14 ×10−3 S m2 mol−1.

    (a)

    5.7 x 10-12

    (b)

    1.32 x 10−12

    (c)

    7.5 x 10−12

    (d)

    1.74 x 10-12

  20. In the electrochemical cell: Zn|ZnSO4 (0.01M)|| CuSO4 (1.0M)|Cu, the emf of this Daniel cell is E1. When the concentration of ZnSO4 is changed to 1.0M and that CuSO4 changed to 0.01M, the emf changes to E2. From the above, which one is the relationship between E1 and E2?

    (a)

    E1 < E2

    (b)

    E1 > E2

    (c)

    E2 ≥ E1

    (d)

    E= E2

  21. Consider the change in oxidation state of Bromine corresponding to different emf values as shown in the diagram below:
    \({ BrO }_{ 4 }^{ - }\overset { 1.82V }{ \longrightarrow } { BrO }_{ 3 }^{ - }\overset { 1.5V }{ \longrightarrow } HBrO\overset { 1.595v }{ \longrightarrow } { Br }_{ 2 }\overset { 1.0652V }{ \longrightarrow } Br^{ - }\)
    Then the species undergoing disproportional is

    (a)

    Br2

    (b)

    BrO4-

    (c)

    BrO-3

    (d)

    HBrO

  22. For the cell reaction
    2Fe3+(aq) + 2l(aq) \(\rightarrow\)2Fe2+ (aq) + 12 (aq)
    Eocell = 0.24V  = at 298K. The standard Gibbs energy (Δ, Go) of the cell reactions is:

    (a)

    -46.32 KJ mol−1

    (b)

    -23.16 KJ mol-1

    (c)

    46.32 KJ mol−1

    (d)

    23.16 KJ mol-1

  23. A certain current liberated 0.504gm of hydrogen in 2 hours. How many grams of copper can be liberated by the same current flowing for the same time in a copper sulphate solution ______.

    (a)

    31.75

    (b)

    15.8

    (c)

    7.5

    (d)

    63.5

  24. A gas X at 1 atm is bubbled through a solution containing a mixture of 1MY- and 1MZ- at 25oC. If the reduction potential of Z>Y>X, then_____.

    (a)

    Y will oxidize X and not Z

    (b)

    Y will oxidize Z and not X

    (c)

    Y will oxidize both X and Z

    (d)

    Y will reduce both X and Z

  25. Cell equation: A + 2B- \(\rightarrow\)A2++ 2B; A2+ + 2e- \(\rightarrow\)A Eo = +0.34V and log10 K = 15.6 at 300K for cell reactions find Eo for B+ + e \(\rightarrow\) B 

    (a)

    0.80

    (b)

    1.26

    (c)

    -0.54

    (d)

    -10.94

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