PPSC Chemistry Lecturer Preparation (Test # 07)- Malik Xufyan 03137355727

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PPSC CHEMISTRY CLASS
Test Session
CH: Electrochemistry
Test # 07
For more WhatsApp # 0313-7355727
Topics:
1. Conductance and its Measurement
2. Activity and Activity Coefficient
3. Measurement of Activity Coefficient
4. Debye-Huckel Theory and its Applications for Strong Electrolytes
Conductance and its Measurement
1. The reciprocal of resistivity of a conductor is
a) Conductance
b) capacitance
c) conductivity
d) none of these
2. The reciprocal of electrical resistance is
a) voltage
b) current
c) conductance
d) none of the above
3. The units for specific conductance is
a) Ohm-1
m-1
b) Ohm-1
cm-1
c) S m-1
d) S cm-1
e) All of these
4. The units for molar conductance is
a) Ohm-1
m2
mol-1
b) S m2
mol-1
c) Both a and b
d) S cm-1
5. The element with the highest conductivity is
a) gold
b) silver
c) copper
d) platinum
6. As temperature increases electrolytic conduction
a) increases
b) decreases

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c) remains unaffected
b) none of the above
7. With a rise in temperature, the resistance of semiconductors
a) decreases
b) increases
c) first, increase and then decrease
d) remains constant
8. Choose the correct order of molar ionic conductivities of the following ions.
a) Li+
< Na+
< K+
< Rb+
b) Li+
< K+
< Rb+
< Na+
c) Li+
< Na+
< Rb+
< K+
d) Li+
< Rb+
< Na+
< K+
9. Equivalent conductance of BaCl2 is equal to
a) Molar conductance of 2BaCl2
b) Molar conductance of BaCl2
c) Molar conductance of ½ BaCl2
d) Molar conductance of 4BaCl2
10. Specific conductance decreases with dilution due to
a) Increase in number of ions per unit volume of solution
b) Decrease in number of ions per unit volume of solution
c) No change in number of ions per unit volume of solution
d) Constant number of ions per unit volume of solution
11. Molar conductance and equivalent conductance of electrolytes
a) Increases with dilution
b) Decreases with dilution
c) No change on dilution
d) Becomes half with dilution
12. Conductance of strong electrolytes
a) Increases with dilution
b) Does not increases with dilution
c) Decrease on dilution
d) Becomes half with dilution
13. Conductance depends upon
a) No. of ions per unit volume
b) Speed of ions
c) Both a and b
d) None of above
14. For weak electrolyte conductance depends upon
a) Value of ΔH
b) Pressure
c) Volume
d) None of these
15. The cell constant is defined as the ratio of ____________
a) Area of either electrodes to the length between the electrodes

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b) Length between the electrodes to the area of either electrodes
c) Length between the electrodes to the volume of either electrode
d) Resistivity to conductivity
16. Conductance is measured by
a) Temperature
b) Pressure
c) Volume
d) Conductivity cells
17. Cell constant can also be defined as the ratio of specific conductance to observed
conductance
a) True
b) False
18. The equivalent conductance of 0.1 H2SO4offering a resistance of 50ohms when
placed in a conductivity cell whose electrodes are 1cm apart with a cross-sectional area
of 2cm2 at 250C is?
a) 100 S cm2
eq-1
b) 1000 S cm2
eq-1
c) 10 S cm2
eq-1
d) 1 S cm2
eq-1
19. The equivalent conductance of Ba2+ and Cl– are respectively 127 and 76 ohm-1 cm-
1 eq-1 at infinite dilution. The equivalent conductance of BaCl2 at infinite dilution will be
a) 139.5
b) 203
c) 279
d) 101.5
20. The weight of silver displaced by a quantity of electricity which displaces 5600ml of
O2 at STP will be
a) 5.4g
b) 10.8g
c) 54.9g
d) 108.0g
Activity, Activity Coefficient and its Measurement
21. Effective concentration or apparent concentration of an electrolyte in a solution is
called activity (ɑ).
a) True
b) False
22. Activity (ɑ) = γm, where γ is called __________ and equal to the ratio of effective
concentration and actual concentration of an electrolyte in a solution.
a) Activity
b) Activity coefficient
c) Active concentration

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d) Concentration
23. The activity coefficient for non-ideal solution is_________
a) less than 1
b) gretar than 1
c) equl to 1
d) non of the above
24. For an electrolyte under ideal condition
a) Effective concentration > Actual concentration
b) Effective concentration < Actual concentration
c) Effective concentration = Actual concentration
d) All of these
25. Activity coefficients generally increase as
a) Ionic strength increases
b) Charge on the ion increases
c) The hydrated ion size increases
d) All of above
26. Under ideal condition for a dilute solution the activity value is equal to
a) 1
b) 2
c) 3
d) 4
27. For a highly concentrated solution effective concentration is ________ than actual
concentration.
a) Less
b) Greater
c) Equal
d) None
28. In an aqueous solution [Fe2+] = [Fe3+] the activity of Fe2+ is
a) Smaller than the activity of Fe3+
b) Larger than the activity of Fe3+
c) Both have same activity
d) None of these
29. Extent of dissociation of an electrolyte depends upon
a) Temperature
b) Concentration
c) Nature of electrolyte
d) All of above
30. Calculate the mean activity for KCl  1K+ + 1Cl-
a) m2
γ2
b) m3
γ3
c) 4m2
γ2
d) 2m2
γ2
31. Calculate the mean activity for Na2SO4  2Na 2+ + SO4
2-
a) m2
γ2

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b) m3
γ3
c) 4m3
γ3
d) 2m2
γ2
Debye-Huckel Theory and its Applications for Strong Electrolytes
32. Debye-Huckel theory for strong electrolyte was given in the year
a) 1923
b) 1930
c) 1940
d) 1950
33. Debye-Huckel theory is applicable to
a) Weak electrolytes
b) Strong electrolytes
c) Semi electrolytes
d) All types of electrolytes
34. According to Debye-Huckel theory under ideal condition (i.e strong electrolyte and
dilute solution) said:
a) Ions have interionic interactions
b) Positive and negative ions exist
c) Electrolyte must be completely ionized
d) All of these
35. Distortion of ionic spheres occurs by which of the following
a) Asymmetric effect
b) Electrophoretic effect
c) Both a and b
d) None
36. Electrophoretic effect is due to
a) External EMF
b) Counter movement of solvent molecules
c) Temperature
d) Pressure
37. Strong electrolytes are completely ionised even in concentrated solution but mobility
of ions is
a) Small
b) Large
c) Moderate
d) Very large
38. Ionic mobility of a strong electrolyte in a concentrated solution is small due to
a) Asymmetric effect
b) Electrophoretic effect
c) Both a and b
d) None

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39. As asymmetric and electrophoretic effect increases conductance of electrolytic solu-
tion ______
a) Increases
b) Decreases
c) Remains constant
d) First increase then decrease
40. Ionic strength _____in concentrated solution and hence activity coefficient ______.
a) Increases, increases
b) Decreases, decreases
c) Decreases, increases
d) Increases, dcreases
41. Ionic strength of an electrolytic solution depends upon
a) Charge of ion
b) Concentration of electrolyte
c) Both a and b
d) None of these
42. Formula for ionic strength (μ) is
a) μ = ½ Ʃ mi Zi
2
b) μ = Ʃ mi Zi
2
c) μ = 2 Ʃ mi Zi
2
d) μ = 2/3 Ʃ mi Zi
2
43. Ionic strength for 0.1m KCl solution is
a) 0.3
b) 0.1
c) 0.5
d) 0.2
44. Ionic strength for 0.1m CaCl2 solution is
a) 0.3
b) 0.1
c) 0.5
d) 0.3
45. Once a current of 1.0 ampere was passed through one litre of CuCl2 solution for 16
min and 5 sec, all of the solution’s copper was deposited at the cathode. The strength of
solution CuCl2 was (Molar mass of Cu = 63.5; Faraday constant = 96,500 C/mol)
a) 0.01N
b) 0.01M
c) 0.02M
d) 0.2N
46. The relationship between ionic strength and activity coefficient is called
a) Arrhenius equation
b) Debye-Huckel limiting law
c) Ostwald Law
d) Law of mass action
47. Debye Huckel Limiting law is

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a) logγ± = − |z+z−| μ
b) logγ± = |z+z−| √ μ
c) logγ± = −0.509|z+z−| √ μ
d) logγ± = −0.509|z+z−| μ
48. Consider a solution of 0.01 M MgCl2 (aq) with an ionic strength of 0.030 M. What is
the mean activity coefficient?
a) 0.67
b) 0.5
c) 0.001
d) 0.8
49. In electrolytic conductors, the conductance is due to _____________
a) Flow of free mobile electrons
b) Movement of ions
c) Either movement of electrons or ions
d) Cannot be said
50. Which of the following are the strong electrolytes?
a) HCl
b) Acetic acid
c) Propinoic acid
d) H2SO3