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#### Electro Chemistry Model Question Paper

12th Standard EM

Reg.No. :
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Chemistry

Time : 01:00:00 Hrs
Total Marks : 50
12 x 1 = 12
1. Faradays 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

2. 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

3. A conductivity cell has been calibrated with a 0.01M, 1:1 electrolytic solution (specific conductance ( k =1.25x10-3cm-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 c m−1

(d)

5.7x10-12

4. Cell equation : A + 2B- $\rightarrow$A2++2B;
A2+ + 2e- $\rightarrow$AEo =+0.34V and log10 K = 15.6 at 300K for cell reactions find Eo for
B1 + e $\rightarrow$

(a)

0.80

(b)

1.26

(c)

-0.54

(d)

-10.94

5. Which among the following is the strongest reducing agent?

(a)

F2

(b)

Cl2

(c)

Zn

(d)

Li

6. Recharging of lead storage battery involves

(a)

anode is reduced to pb

(b)

cathode is reduced to pb

(c)

cathode is oxidised to pb

(d)

anode is oxidised to pbO2

7. When one coulomb of electricity is passed through an electrolytic solution) the mass deposited on the electrode is equal to

(a)

equivalent weight

(b)

molecular weight

(c)

electrochemical equivalent

(d)

one gram

8. The important use of Kohlrausch's law is deducing the

(a)

λ value of weak electrolyte.

(b)

λ value of strong electrolyte.

(c)

λ value of weak electrolyte.

(d)

λ value of weak electrolyte

9. Calculate the standard emf of the cell, provided the standard reduction potentials of cathode and anode are -0.763 V and 0.80V.

(a)

- 1.563V

(b)

0.037V

(c)

- 0.610V

(d)

None of these

10. In Daniel cell, the charges developed by Zn/Zn2+ and Cu / Cu2+ are _________

(a)

positive, positive

(b)

negative, negative

(c)

positive, negative

(d)

negative, positive

11. The emf of the cell is measured in _________

(a)

ohm

(b)

amperes

(c)

volts

(d)

coulomb

12. The feasibility of a redox reaction can be predicted with the help of ________

(a)

reduction potential

(b)

oxidation potential

(c)

electrochemical series

(d)

standard emf

13. 2 x 2 = 4
14. Assertion: Increase in temperature, decreases conductance
Reason: This is due to the increase in the attractive forces between the oppositely charged ions
a) (A) and (R) are true and (R) is the correct explanation of (A)
b) Both (A) and (R) are true but (R) does not explain (A)
c) (A) is true but (R) is false
d) Both (A) and (R) are false

15. Assertion: The relationship between ΔG and emf of cell is ΔG = -nFE
Reason : In the Nemst equation, 'n' denotes number of protons
a) (A) and (R) are true and (R) is the correct explanation of (A)
b) Both (A) and (R) are true but (R) does not explain (A)
c) (A) is true but (R) is false
d) Both (A) and (R) are false

16. 5 x 2 = 10
17. Why does conductivity of a solution decrease on dilution of the solution

18. The resistance of a conductivity cell is measured as 190 Ω using 0.1M KCl solution (specific conductance of 0.1M KCl is 1.3 Sm-1) . When the same cell is filled with 0.003M sodium chloride solution, the measured resistance is 6.3KΩ. Both these measurements are made at a particular temperature. Calculate the specific and molar conductance of NaCl solution. Given that

19. Define conductance. Give its unit

20. Give the expression that relates molar conductivity and degree of dissociation.

21. The standard reduction potentials of Fe3+ / Fe and Fe2+ / Fe electrode system are -0.035 V and -0.44 V respectively. Predict which of the two oxidations is easy. Fe3+ / Fe and Fe2+ / Fe

22. 3 x 3 = 9
23. Arrange the following solutions in the decreasing order of specific conductance.
i) 0.01M KCl
ii) 0.005M KCl
iii) 0.1M KCl
iv) 0.25 M KCl
v) 0.5 M KCl

24. What is the oxidation and reduction half cell in a Daniel cell?

25. Draw a neat diagram of Leclanche cell and mark the parts.

26. 3 x 5 = 15
27. Ionic conductance at infinite dilution of Al3+ and SO4 2- are 189 and 160 mho cm2 equiv-1. Calculate the equivalent and molar conductance of the electrolyte Al2 (SO4)3 at infinite dilution.

28. Specific conductance of 1M KNO3 solution is oberved to be 5.55 x 10-3 mho cm2. What is the equivalent conductance of KNO3 when one litre of the solution is used?

29. Write an account on cell terminology.