10 ElectroChemistry Quiz | Chemistry Quiz
Electrolytes and Electrolysis
(1) Definition: “The substances whose aqueous solution undergo decomposition into ions when an electric current is passed through them are known as electrolytes and the whole process is known as electrolysis or electrolytic decomposition.”
Solutions of acids, bases, salts in water and fused salts etc. are the examples of electrolytes. Electrolytes may be weak or strong. Solutions of cane sugar, glycerine, alcohol etc., are examples of non-electrolytes.
(2) Electrolytic cell or Voltameter: The device in which the process of electrolysis or electrolytic decomposition is carried out is known as electrolytic cell or voltameter.
(i) Voltameter converts electrical energy into chemical energy.
(ii) The electrode on which oxidation takes place is called anode (or +ve pole) and the electrode on which reduction takes place is called cathode (or –ve pole)
(iii) During electrolysis in voltameter, cations are discharged on cathode and anions on the anode.
(iv) In voltameter, outside the electrolyte electrons flow from anode to cathode and current flow from the cathode to anode.
Electrolytes and Electrolysis Quiz
(a) Are partially ionized
(b) Do not ionise
(c) Ionise almost completely
(d) Form polymers
S0l: (c) Strong electrolytes are almost completely ionised in polar solvent.
2. An electrolyte
(a) Forms complex ions in solution
(b) Gives ions only when electricity is `passed
(c) Possesses ions even in solid state
(d) Gives ions only when dissolved in water
3. Electrolytes when dissolved in water dissociates into ions because
(a) They are unstable
(b) The water dissolves it
(c) The force of repulsion increases
(d) The forces of electrostatic attraction are broken down by water
4. The electrolyte can conduct electricity because
(a) Their molecules contain unpaired electrons, which are mobile
(b) Their molecules contain loosely held electrons which get free under the influence of voltage
(c) The molecules break up into ions when a voltage is applied
(d) The molecules are broken up into ions when the electrolyte is fused or is dissolved in the solvent
5. When the sample of copper with zinc impurity is to be purified by electrolysis, the appropriate electrodes are
(a) Pure zinc Pure copper
(b) Impure sample Pure copper
(c) Impure zinc Impure sample
(d) Pure copper Impure sample
S0l: (d) Impure metal made anode while pure metal made cathode.
6. In the electrolytic cell, flow of electrons is from
(a) Cathode to the anode in the solution
(b) Cathode to the anode through external supply
(c) Cathode to the anode through the internal supply
(d) Anode to the cathode through the internal supply
S0l: (d) In electrolytic cell, cathode acts as source of electrons.
7. An electric current is passed through an aqueous solution of the following. Which one shall decompose
d) Ethyl alcohol
S0l: (c) AgNO3 is an electrolyte.
8. The addition of a polar solvent to a solid electrolyte results in
(d) Non-liberation of heat
S0l: (c) When polar solvent added in to solid electrolyte than it is ionised.
9. During the electrolysis of fused which reaction occurs at anode
(a) Chloride ions are oxidized
(b) Chloride ions are reduced
(c) Sodium ions are oxidised
(d) Sodium ions are reduced
S0l: (a) In fused chloride ions are oxidized at anode and it is called oxidation.
10. The amount of ion discharged during electrolysis is not directly proportional to
(d) Chemical equivalent of the ion
S0l: (a) .
11. Pure water does not conduct electricity because it
(a) Has a low boiling point
(b) Is almost totally unionized
(c) Is neutral
(d) Is readily decomposed
S0l: (b) Because it does not have ions.
12. Which is responsible for electrical conduction of molten sodium chloride
(a) Free electrons
(b) Free ions
(c) Free molecules
(d) Atoms of sodium and chlorine
S0l: (b) .
13. Use of electrolysis is
(c) (a) and (b) both
(d) None of these
S0l: (c) Electrolysis use for electroplating and electrorefining.
Faraday’s law of electrolysis Quiz
14. The unit of electrochemical equivalent is
15. If the current is passed into the solution of an electrolyte
(a) Anions move towards anode, cations towards cathode
(b) Anions and cations both move towards anode
(c) Anions move towards cathode, cations towards anode
(d) No movement of ions takes place
16. Unit of Faraday is
(a) Ampere (b) Coulomb
(c) Coulomb /mole (d) Coulomb /sec
17. How many Faradays are required to generate one gram atom of magnesium from MgCl2
(a) 1 (b) 2
(c) 3 (d) 4
18. In electrolysis of a fused salt, the weight of the deposit on an electrode will not depend on]
(a) Temperature of the bath
(b) Current intensity
(c) Electrochemical equivalent of ions
(d) Time for electrolysis
S0l: (a) The amount deposited is directly proportional to current intensity, electrochemical equivalent of ions and the time for electrolysis and is independent of the temperature.
19. A current being passed for two hour through a solution of an acid liberating 11.2 litre of oxygen at NTP at anode. What will be the amount of copper deposited at the cathode by the same current when passed through a solution of copper sulphate for the same time
(a) 16 g (b) 63 g
(c) 31.5 g (d) 8 g
S0l: (b)Equivalent wt. of O2= Equivalent wt. of Cu
20. In a metal oxide, there is 20% oxygen by weight. Its equivalent weight is
(a) 40 (b) 64
(c) 72 (d) 32
21. The electrolytic cells, one containing acidified ferrous chloride and another acidified ferric chloride are connected in series. The ratio of iron deposited at cathodes in the two cells when electricity is passed through the cells will be
(a) 3 : 1 (b) 2 : 1
(c) 1 : 1 (d) 3 : 2
22. When 96500 coulomb of electricity is passed through a copper sulphate solution, the amount of copper deposited will be
(a) 0.25 mol (b) 0.50 mol
(c) 1.00 mol (d) 2.00 mol
S0l: (b) 31.75 g copper gets deposited at cathode on passing 96500 coulomb charge. We know that 31.75 gm of Cu is equal to 0.5 mole of Cu deposited at cathode on passing 1F of current
23. During electrolysis of fused aluminium chloride 0.9gm of aluminium was deposited on the cathode. The volume of chlorine liberated at the anode will be
(a) 2.24 litres (b) 11.2 litres
(c) 1.12 litres (d) 5.6 litres
24. When one of ampere current flows for through a conductor, this quantity of electricity is known as
(a) Faraday (b) Coulomb
(c) E.M.F. (d) Ohm
25. The mass deposited at an electrode is directly proportional to
(a) Atomic weight
(b) Equivalent weight
(c) Molecular weight
(d) Atomic number
26. On electrolysis, 1 mole of aluminium will be deposited from its molten salt by
(a) 3 moles of electrons
(b) 4 moles of electrons
(c) 2 moles of electrons
(d) 1 mole of electrons
S0l: (a) .
Conductor and Conductance Quiz
27. The conductivity of strong electrolyte is
(a) Increase on dilution slightly
(b) Decrease on dilution
(c) Does not change with dilution
(d) Depend upon density of electrolytes itself
S0l: (a) Generally strong electrolyte on dilution shows conductivity characters.
28. The molar conductivity is maximum for the solution of concentration
(a) 0.001 M (b) 0.005 M
(c) 0.002 M (d) 0.004 M
29. The highest electrical conductivity of the following aqueous solutions is of
(a) 0.1 M acetic acid
(b) 0.1 M chloroacetic acid
(c) 0.1 M fluoroacetic acid
(d) 0.1 M difluoroacetic acid
30. Which of the following shows electrical conduction
(a) Potassium (b) Graphite
(c) Diamond (d) Sodium
S0l: (b) Graphite is a good conductor of electricity.
31. The electrolytic conductance is a direct measure of
S0l: (d) Because conductance is increase when the dissociation is more.
32. The conductivity of a strong electrolyte
(a) Increases on dilution
(b) Does not change considerably on dilution
(c) Decreases on dilution
(d) Depends on density
S0l: (b) Strong electrolyte ionize completely at all dilutions and the number of ions does not increase on dilution. A small increase in volume with dilution is due to the weakening of electrostatic attraction between the ions on dilution.
33. Which of the following statements is not applicable to electrolytic conductors
(a) New products show up at the electrodes
(b) Ions are responsible for carrying the current
(c) Show a positive temperature coefficient for conductance
(d) A single stream of electrons flows from cathode to anode
S0l: (d) In electrolytic conductors, a single stream of electrons flow from cathode to anode.
34. Solid sodium chloride is bad conductor of electricity because
(a) It contains only molecules
(b) It does not possess ions
(c) The ions present in it are not free to move
(d) It does not contain free molecules
S0l: (c) The ions are not free to move in solid state and held up in lattice due to strong coulombic forces of attraction.
Cell constant and Electrochemical cells Quiz
35. When lead storage battery is charged
(a) Lead dioxide dissolves
(b) Sulphuric acid is regenerated
(c) The lead electrode becomes coated with lead sulphate
(d) The amount of sulphuric acid decreases
S0l: (b) During charging of a lead storage battery, the reaction at the anode and cathode
36. The electrolytic decomposition of dilute sulphonic acid with platinum electrode in cathodic reaction is
(c) Oxidation and reduction both
37. Hydrogen–oxygen fuel cells are used in space–craft to supply
(a) Power for heat and light
(b) Power for pressure
S0l: (b) Fuel-cells are used to provide power and drinking water to astronauts in space programme.
38. Which of the following statements about galvanic cell is incorrect
(a) Anode is positive
(b) Oxidation occurs at the electrode with lower reduction potential
(c) Cathode is positive
(d) Reduction occurs at cathode
S0l: (a) Anode has negative polarity.
39. If the conductance and specific conductance of a solution is one then its cell constant would be
(a) 1 (b) Zero
(c) 0.5 (d) 4
S0l: (a) .
40. Which of the following is used widely in the manufacture of lead storage battery
(a) Arsenic (b) Lithium
(c) Bismuth (d) Antimony
Electrode potential, Ecell, Nernst equation and ECS Quiz
41. Oxidation and reduction take place in a cell, then its electromotive force will be
(a) Positive (b) Negative
(c) Zero (d) Stable
S0l: (a) Electromotive force is +ve if oxidation and reduction both takes place in a cell.
42. Which one of the following metals cannot evolve from acids or or from its compounds
(a)Hg (b) Al
(c) Pb (d) Fe
S0l: (a) Hg has greater reduction potential than that of H+ and hence cannot displace hydrogen from acid.
43. If the reduction potential is more, then
(a) It is easily oxidised
(b) It is easily reduced
(c) It acts as oxidising agent
(d) It has redox nature
44. One of the following is false for Hg
(a) It can evolve hydrogen from H2S
(b) It is a metal
(c) It has high specific heat
(d) It is less reactive than hydrogen
45. In which cell the free energy of a chemical reaction is directly converted into electricity ?
(a) Leclanche cell (b) Concentration cell
(c) Fuel cell (d) Lead storage battery
S0l: (c) Fuel cell converts the chemical energy into electrical energy.