TEST--54--XII [electro-]

Q.15.- Which of the following statements about a salt bridge in a voltaic cell is TRUE?

1. Free electrons flow through the salt bridge to maintain electrical neutrality in the two half-cells.
2. The salt bridge allows the ions present in the two half-cells to mix extensively.
3. The wire must be connected directly to the salt bridge in order for the salt bridge to be able to maintain electrical neutrality in the two half-cells.
4. In some cases, a salt bridge functions as the anode.
5. Ions from the electrolyte in the salt bridge flow into each half-cell to maintain electrical neutrality.

TEST--54--XII [electro-]

Q.14.- The reaction ½ H2(g) + AgCl(s) = H⁺(aq) + Cl^-
(aq) +Ag(s) occurs in the galvanic cell:

a. Ag|AgCl(s) |KCl(soln) |AgNO3(soln) |Ag
b.Pt|H2(g) |HCl(soln) |AgNO3(soln) |Ag
c. Pt|H2(g) |HCl(soln) |AgCl(s) |Ag
d. Pt|H2(g) |KCl(soln) |AgCl(s) |Ag
(JEE 1985)

TEST--54--XII [electro-]

Q.13.- The electric charge or electrode deposition of one gram equivalent of a substance is:

a. one ampere for one second
b. 96,500 coulombs per second
c. one ampere for one hour
d. charge on one mole of electrons
(JEE 1984)

TEST--54--XII [electro-]

Q.12.- A solution containing one mole for litre each of Cu(NO3)2, AgNO3, Hg2(NO3)2 and Mg(NO3)2 is electrolysed using inert electrodes.
Standard electrode potentials in volts (reduction potentials) are:

Ag⁺| Ag = 0.80
Hg2²⁺ |Hg = 0.79
Cu²⁺|Cu = 0.34
Mg²⁺|Mg = -2.37

With increasing voltage, the sequence of deposition of metals on the cathode will be:


a. Ag,Hg,Cu, Mg
b. Mg,Cu,Hg,Ag
c. Ag,Hg, Cu
d. Cu,Hg, Ag

TEST--54--XII [electro-]

Q.11.- Faraday’s laws of electrolysis are related to the

a. atomic number of the cation.
b. atomic number of the anion.
c. equivalent weight of the electrolyte
d. speed of the cation
(JEE 1983)

TEST--54--XII [electro-]

Q.10.-Given the balanced equation:
2Al(s) + 6H⁺(aq) -> 2Al³⁺(aq) + 3H₂
When 2 moles of Al(s) completely reacts, what is the total number of moles of electrons transferred from Al(s) to H⁺(aq)?

1. 5
2. 6
3. 3
4. 4

TEST--54--XII [electro-]

Q.9.-Given the reaction for the nickel-cadmium battery:
2NiOH + Cd +2H₂O -> 2Ni(OH)₂ + Cd(OH)₂
What species is oxidized during the discharge of the battery?

1. Ni³⁺
2. Ni²⁺
3. Cd
4. Cd²⁺

TEST--54--XII [electro-]

Q.8.-Which substance functions as the electrolyte in an automobile battery?

1. PbO₂
2. PbSO₄
3. H₂SO₄
4. H₂O

TEST--54--XII [electro-]

Q.7.-What is the number of Faradays (moles of electrons) required to produce 9.0g of aluminum by the electrolysis of molten aluminum oxide, Al₂O₃?

a) 9 F b) 4F c) 3F d) 2F e) 1F

TEST--54--XII [electro-]

An electric current is applied to an aqueous solution of FeCl₂ and ZnCl₂. Which reaction occurs at the cathode?

a) Fe²⁺_(aq) + 2e^-_(aq) à Fe_(s) E˚_red=-0.44V

b) Fe_(s) à Fe²⁺ _(aq) + 2e^- E˚_ox=0.44V

c) Zn⁺²_(aq) + 2e^-_(aq) à Zn_(s) E˚_red=-0.76V

d) Zn_(s) à Zn²⁺ _(aq) + 2e^- E˚_ox=0.76V

e) 2H₂O_(l) à O_2(g) + 4H⁺_(aq) + 4e- E˚_ox=-1.23V

Q.6.-Which of the following is FALSE.

a) The magnesium electrode is being oxidized to Mg⁺²

b) The aluminum electrode is the cathode

c) The magnesium electrode is the anode

d) The aluminum ions are being reduced

e) The positive ions will flow from the Al compartment to the Mg compartment

TEST--54--XII [electro-]

Q.2.-Which of the following compounds includes and element with an oxidation number of +5?

a) ClO₄^- b) MnO₄^- c) NO₂^- d) SO₃^2- e) NO₃^-

Q.3.- Which of the following metals does NOT react with water to produce hydrogen?

a) Zn b) Li c) Ca d) Na e) K

Q.4.- The standard voltage, E˚, is 0.68V for the cell: In| In⁺³ || Cu⁺²| Cu

Find the standard reduction potential for the reaction: In⁺³ + 3e- à In

a) 0.34V b) –0.34V c) 1.02V d) –1.02V e) 0.00V

Q.5.- Given the following information, which of the statements is true?

Cu²⁺ _(aq) + e- à Cu⁺_(aq) E˚_red= 0.34V

2H⁺_(aq) + 2e- à H_2(g) E˚_red= 0.0V

Fe⁺²_(aq) + 2e- à Fe_(s) E˚_red= -0.44V

Ni_(s) à Ni⁺²_(aq) + 2e- E˚_red= 0.25V

a) Cu⁺²_(aq) is the strongest oxidizing agent

b) Cu⁺²_(aq) is the weakest oxidizing agent

c) Ni_(s) is the strongest oxidizing agent

d) Fe_(s) would be the weakest reducing agent

e) H⁺_(aq) would be the strongest oxidizing agent

TEST--54--XII [electro-]

Q .1.- Chlorine gas is an important industrial chemical produced by electrolysis. How many moles of electrons are required to prepare 1.000 metric ton (1000. kg) of chlorine gas by electrolysis of an aqueous solution of sodium chloride?

2 NaCl(aq) + 2 H₂O(l) -> 2 NaOH(aq) + H₂(g) + Cl₂(g)

How many faradays? How many coulombs? Assume that the efficiency of the electrochemical cell is 100%; that is, every electron involved results in the production of a chlorine atom.

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