Electrochemistry Test 4

Total Questions:50 Total Time: 75 Min



Questions 1 of 50

Question:Which colourless gas evolves, when \(N{H_4}Cl\) reacts with zinc in a dry cell battery

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Questions 2 of 50

Question:Which of the substances \(Na,\,\,Hg,\,\,S,\,\,Pt\) and graphite can be used as electrodes in electrolytic cells having aqueous solutions

Answers Choices:

\(Na,\,\,Pt\)and graphite

\(Na\)and \(Hg\)

\(Pt\)and graphite only

\(Na\)and \(Al\)only

Questions 3 of 50

Question:In electrolysis of dilute \({H_2}S{O_4}\)using platinum electrodes

Answers Choices:

\({H_2}\) is evolved at cathode

\(N{H_3}\) is produced at anode

\(C{l_2}\) is obtained at cathode

\({O_2}\) is produced

Questions 4 of 50

Question:Saturated solution of \(KN{O_3}\) is used to make ‘salt-bridge’ because

Answers Choices:

Velocity of \({K^ + }\) is greater than that of \(NO_3^ - \)

Velocity of \(NO_3^ - \) is greater than that of \({K^ + }\)

Velocities of both \({K^ + }\)and \(NO_3^ - \) are nearly the same

\(KN{O_3}\)is highly soluble in water

Questions 5 of 50

Question:In balancing the half reaction \({S_2}O_3^{2 - } \to {S_{(s)}}\) the number of electrons that must be added is

Answers Choices:

4 on the left

3 on the right

2 on the left

2 on the right

Questions 6 of 50

Question:Which one of the following statement is true for a electrochemical cell

Answers Choices:

\({H_2}\)is cathode and \(Cu\) is anode

\({H_2}\) is anode and \(Cu\) is cathode

Reduction occurs at \({H_2}\)electrode

Oxidation occurs at \(Cu\) electrode

Questions 7 of 50

Question:In a electrochemical cell

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Potential energy changes into kinetic energy

Kinetic energy changes into potential energy

Chemical energy changes into electrical energy

Electrical energy changes into chemical energy

Questions 8 of 50

Question:In galvanic cell, the salt bridge is used to

Answers Choices:

Complete the circuit

Reduce the electric resistance in the cell

Separate cathode from anode

Carry salts for the chemical reaction

Questions 9 of 50

Question:If hydrogen electrode dipped in 2 solution of \(pH = 3\) and \(pH = 6\) and salt bridge is connected the e.m.f. of resulting cell is

Answers Choices:

0.177 V

0.3 V

0.052 V

0.104 V

Questions 10 of 50

Question:The tendency of an electrode to lose electrons is known as

Answers Choices:

Electrode potential

Reduction potential

Oxidation potential


Questions 11 of 50

Question:It has been observed that gaseous hydrogen chloride is a very poor conductor of electricity but a solution of hydrogen chloride gas in water is a good conductor of electricity. This is due to the fact that

Answers Choices:

Water is good conductor of electricity

Hydrogen chloride gas in water solution ionizes

A gas is non-conductor but a liquid conducts electricity

Gas does not obey Ohm's law whereas solution does

Questions 12 of 50

Question:Electrolytic conduction differs from metallic conduction in that in the case of electrolytic conduction

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The resistance increases with increasing temperature

The resistance decreases with increasing temperature

The flow of current does not generate heat

The resistance is independent of the length of the conductor

Questions 13 of 50

Question:Which of the following is a highly corrosive salt

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Questions 14 of 50

Question:Corrosion of iron is essentially an electrochemical phenomenon where the cell reactions are

Answers Choices:

\(Fe\) is oxidised to \(F{e^{2 + }}\) and dissolved oxygen in water is reduced to \(\mathop {OH}\limits^ \oplus \)

\(Fe\) is oxidised to \(F{e^{3 + }}\) and \({H_2}O\) is reduced to \(O_2^{2 - }\)

\(Fe\) is oxidised to \(F{e^{2 + }}\) and \({H_2}O\) is reduced to \(O_2^ - \)

\(Fe\) is oxidised to \(F{e^{2 + }}\) and \({H_2}O\) is reduced to \({O_2}\)

Questions 15 of 50

Question:\({E^0} = \frac{{RT}}{{nF}}\) In \({K_{eq}}\). This is called

Answers Choices:

Gibb's equation

Gibb's–Helmholtz equation

Nernst's equation

Vander Waal's equation

Questions 16 of 50

Question:Four alkali metals A, B, C and D are having respectively standard electrode potential as –3.05,–1.66,–0.40 and 0.80. Which one will be the most reactive

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Questions 17 of 50

Question:If an iron rod is dipped in \(CuS{O_4}\) solution

Answers Choices:

Blue colour of the solution turns green

Brown layer is deposited on iron rod

No change occurs in the colour of the solution

Blue colour of the solution vanishes

None of the above

Questions 18 of 50

Question:\({E^o}\) values of \(M{g^{2 + }}/Mg\) is \( - 2.37V\), of \(Z{n^{2 + }}/Zn\) is \( - 0.76V\) and \(F{e^{2 + }}/Fe\) is \( - 0.44\,V\). Which of the following statements is correct

Answers Choices:

\(Zn\) will reduce \(F{e^{2 + }}\)

\(Zn\) will reduce \(M{g^{2 + }}\)

\(Mg\) oxidises \(Fe\)

\(Zn\) oxidises \(Fe\)

Questions 19 of 50

Question:Expression representing the cell potential \((E\,\,cell)\)

Answers Choices:

\({E_{{\rm{cathode}}}} + {E_{{\rm{anode}}}}\)

\({E_{{\rm{anode}}}} - {E_{{\rm{cathode}}}}\)

\({E_{{\rm{cathode}}}}- {E_{{\rm{anode}}}}\)

\({{\rm{E}}_{{\rm{left}}}}- {E_{{\rm{right}}}}\)

Questions 20 of 50

Question:Iron displaces copper from its salt solution, because

Answers Choices:

Atomic number of iron is less than that of copper

The standard reduction potential of iron is less than that of copper

The standard reduction potential of iron is more than that of copper

The iron salt is more soluble in water than the copper salt

Questions 21 of 50

Question:Which of the following displaces \(B{r_2}\) from an aqueous solution containing bromide ions

Answers Choices:


\(C{l^ - }\)


\(I_3^ - \)

Questions 22 of 50

Question:For the cell reaction \(C{u^{2 + }}({C_1}aq) + Zn(s) = Z{n^{2 + }}({C_2}aq) + Cu(s)\) of an electrochemical cell, the change in free energy at a given temperature is a function of

Answers Choices:

ln \(({C_1})\)

ln \(({C_2})\)

ln \(({C_1} + {C_2})\)

ln \(({C_2}/{C_1})\)

Questions 23 of 50

Question:\(KMn{O_4}\) acts as an oxidising agent in the neutral medium and gets reduced to \(Mn{O_2}\). The equivalent weight of \(KMn{O_4}\) in neutral medium

Answers Choices:

mol. wt/2


mol. wt/4

mol .wt/7

Questions 24 of 50

Question:Which of the following condition will increase the voltage of the cell, represented by the equation \(C{u_{(s)}} + 2A{g^ + }_{(aq)} \to C{u^{2 + }}_{(aq)} + 2A{g_{(s)}}\)

Answers Choices:

Increase in the concentration of \(A{g^ + }\)ion

Increase in the concentration of \(C{u^ + }\) ion

Increase in the dimension of silver electrode

Increase in the dimension of copper electrode

Questions 25 of 50

Question:\(C{u^ + }\) ion is not stable in aqueous solution because of disproportionation reaction. \({E^o}\) value for disproportionation of \(C{u^ + }\) is (Given \(E_{C{u^{2 + }}/C{u^ + }}^o = 0.15\), \(E_{C{u^{2 + }}/Cu}^o = 0.34V\))

Answers Choices:

0.49 V

0.49 V

0.38 V

0.38 V

Questions 26 of 50

Question:\({E^o}\) of a cell \(aA + bB \to cC + dD\) is

Answers Choices:

\( - \frac{{RT}}{{nF}}\log \frac{{{{[C]}^c}{{[D]}^d}}}{{{{[A]}^a}{{[B]}^b}}}\)

\( - RT\,\log \frac{{{{[a]}^A}{{[b]}^B}}}{{{{[a]}^C}{{[d]}^D}}}\)

\( - \frac{{RT}}{{nF}}\log \frac{{{{[C]}^c}{{[d]}^D}}}{{{{[A]}^a}{{[B]}^b}}}\)

\( - \frac{{RT}}{{nF}}\log \frac{{{{[C]}^c}{{[d]}^D}}}{{{{[a]}^A}{{[B]}^b}}}\)

Questions 27 of 50

Question:A galvanic cell with electrode potential of \('A' = + 2.23\;V\)and \('B' = - 1.43\;V\). The value of \(E{^\circ _{cell}}\) is

Answers Choices:

3.66 V

0.80 V

0.80 V

3.66 V

Questions 28 of 50

Question:The e.m.f. of a cell whose half cells are given below is \(M{g^{2 + }} + 2{e^ - } \to Mg(s)\;E^\circ = - 2.37\;V\)\(C{u^{2 + }} + 2{e^ - } \to Cu(s)\;E^\circ = + 0.34\;V\)

Answers Choices:

+ 1.36 V

+ 2.71 V

+ 2.17 V

3.01 V

Questions 29 of 50

Question:Calculate the electrode potential at \({298^o}K\) for \(Zn|Z{n^{ + + }}\)electrode in which the activity of zinc ions is 0.001 M and \({E^o}_{Zn/Z{n^{ + + }}}\)is –0.74 volts

Answers Choices:

0. 38 volts

0.83 volts

0.40 volts

0.45 volts

Questions 30 of 50

Question:Which of the following expression is correct

Answers Choices:

\(\Delta {G^o} = - nFE_{cell}^o\)

\(\Delta {G^o} = + nFE_{cell}^o\)

\(\Delta {G^o} = - 2.303RT\,nFE_{cell}^o\)

\(\Delta {G^o} = - nF\,\log {K_C}\)

Questions 31 of 50

Question:An electric current is passed through an aqueous solution of the following. Which one shall decompose

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Ethyl alcohol

Questions 32 of 50

Question:The electric conduction of a salt solution in water depends on the

Answers Choices:

Shape of its molecules

Size of its molecules

Size of solvent molecules

Extent of its ionization

Questions 33 of 50

Question:Electrolysis is a process in which the cations and anions of the electrolyte are

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Questions 34 of 50

Question:Degree of ionisation of a solution depends upon

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Nature of the electrolyte

Nature of the solvent

None of these

Questions 35 of 50

Question:An apparatus used for the measurement of quantity of electricity is known as a

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Questions 36 of 50

Question:The unit of electrochemical equivalent is

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Questions 37 of 50

Question:How many Faradays are required to generate one gram atom of magnesium from \(MgC{l_2}\)

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Questions 38 of 50

Question:To deposit 0.6354 gm of copper by electrolysis of aqueous cupric sulphate solution, the amount of electricity required (in coulombs) is

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Questions 39 of 50

Question:Then during electrolysis of a solution of AgNO3, 9650 coulombs of charge pass through the electroplating bath, the mass of silver deposited in the cathode will be

Answers Choices:

1.08 g

10.8 g

21.6 g

108 g

Questions 40 of 50

Question:Total charge on 1 mole of a monovalent metal ion is equal to

Answers Choices:

\(9.65 \times {10^4}\,\,\,Coulomb\)

\(6.28 \times {10^{18}}\,\,\,Coulomb\)

\(1.6 \times {10^{ - 19}}\,\,\,Coulomb\)

None of these

Questions 41 of 50

Question:When an electric current is passed through acidulated water 112 ml of hydrogen gas at N.T.P. collect at the cathode in 965 seconds. The current passed, in amperes is

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Questions 42 of 50

Question:A current of strength 2.5 amp was passed through \(CuS{O_4}\) solution for 6 minutes 26 seconds. The amount of copper deposited is (Atomic weight of \(Cu = 63.5\))(1 faraday = 96500 coulombs)

Answers Choices:

0.3175 g

3.175 g

0.635 g

6.35 g

Questions 43 of 50

Question:A certain quantity of electricity is passed through an aqueous solution of \(AgN{O_3}\) and cupric salt solution connected in series. The amount of \(Ag\) deposited is \(1.08\,gm\), the amount of copper deposited is (atomic weight of Cu = 63.5; Ag = 108)

Answers Choices:

0.6454 g

6.354 g

0.3177 g

3.177 g

Questions 44 of 50

Question:The number of electrons required to deposit 1gm atom of aluminium (at. wt. = 27) from a solution of aluminium chloride will be (where N is Avogadro's number)

Answers Choices:

1 N

2 N

3 N

4 N

Questions 45 of 50

Question:2.5 F of electricity are passed through a \(CuS{O_4}\) solution. The number of gm equivalent of Cu deposited on anode is

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Questions 46 of 50

Question:The equivalent weight of a certain trivalent element is 20. Molecular weight of its oxide is

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Questions 47 of 50

Question:Silver is removed electrically from 200 ml of a 0.1 N solution of \(AgN{O_3}\) by a current of 0.1 ampere. How long will it take to remove half of the silver from the solution

Answers Choices:

16 sec

96.5 sec

100 sec

10 sec

Questions 48 of 50

Question:An electric current is passed through silver nitrate solution using silver electrodes. 10.79 g of silver was found to be deposited on the cathode if the same amount of electricity is passed through copper sulphate solution using copper electrodes, the weight of copper deposited on the cathode is

Answers Choices:

6.4 g

2.3 g

12.8 g

1.6 g

3.2 g

Questions 49 of 50

Question:The law of electrolysis were proposed by

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Questions 50 of 50

Question:How many atoms of calcium will be deposited from a solution of \(CaC{l_2}\)by a current 0.25 mA following for 60 seconds

Answers Choices:

\(4.68 \times {10^{18}}\)

\(4.68 \times {10^{15}}\)

\(4.68 \times {10^{12}}\)

\(4.68 \times {10^9}\)