# Electrochemistry Test 4

Total Questions:50 Total Time: 75 Min

Remaining:

## Questions 1 of 50

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

$$N{H_4}$$

$${N_2}$$

$${H_2}$$

$$C{l_2}$$

## 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

$$Na,\,\,Pt$$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

$${H_2}$$ 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

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

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

$${H_2}$$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

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

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

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

Electrode potential

Reduction potential

Oxidation potential

e.m.f.

## 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

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

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

$$FeC{l_2}$$

$$PbC{l_2}$$

$$H{g_2}C{l_2}$$

$$HgC{l_2}$$

## Questions 14 of 50

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

$$Fe$$ 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

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

A

B

C

D

## Questions 17 of 50

Question:If an iron rod is dipped in $$CuS{O_4}$$ solution

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

$$Zn$$ 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 $$(E\,\,cell)$$

$${E_{{\rm{cathode}}}} + {E_{{\rm{anode}}}}$$

$${E_{{\rm{anode}}}} - {E_{{\rm{cathode}}}}$$

$${E_{{\rm{cathode}}}}- {E_{{\rm{anode}}}}$$

$${{\rm{E}}_{{\rm{left}}}}- {E_{{\rm{right}}}}$$

## Questions 20 of 50

Question:Iron displaces copper from its salt solution, because

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

$$C{l_2}$$

$$C{l^ - }$$

$${I_2}$$

$$I_3^ -$$

## 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

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

mol. wt/2

mol.wt/3

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 $$C{u_{(s)}} + 2A{g^ + }_{(aq)} \to C{u^{2 + }}_{(aq)} + 2A{g_{(s)}}$$

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 $$E_{C{u^{2 + }}/C{u^ + }}^o = 0.15$$, $$E_{C{u^{2 + }}/Cu}^o = 0.34V$$)

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

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

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

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

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

## 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

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 $$M{g^{2 + }} + 2{e^ - } \to Mg(s)\;E^\circ = - 2.37\;V$$$$C{u^{2 + }} + 2{e^ - } \to Cu(s)\;E^\circ = + 0.34\;V$$

+ 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

0. 38 volts

0.83 volts

0.40 volts

0.45 volts

## Questions 30 of 50

Question:Which of the following expression is correct

$$\Delta {G^o} = - nFE_{cell}^o$$

$$\Delta {G^o} = + nFE_{cell}^o$$

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

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

## Questions 31 of 50

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

Urea

Glucose

$$AgN{O_3}$$

Ethyl alcohol

## Questions 32 of 50

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

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

Hydrated

Hydrolysed

Charged

Discharged

## Questions 34 of 50

Question:Degree of ionisation of a solution depends upon

Temperature

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

Calorimeter

Cathetometer

Coulometer

Colorimeter

## Questions 36 of 50

Question:The unit of electrochemical equivalent is

Gram

Gram/ampere

Gram/coulomb

Coulomb/gram

## Questions 37 of 50

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

1

2

3

4

## 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

9650

4825

3860

1930

## 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

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

$$9.65 \times {10^4}\,\,\,Coulomb$$

$$6.28 \times {10^{18}}\,\,\,Coulomb$$

$$1.6 \times {10^{ - 19}}\,\,\,Coulomb$$

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

1

0.5

0.1

2

## 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)

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)

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)

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

Zero

1.25

2.5

5

## Questions 46 of 50

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

152

56

168

68

## 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

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

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

Kohlraush

Nernst

Berthelot

## 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

$$4.68 \times {10^{18}}$$
$$4.68 \times {10^{15}}$$
$$4.68 \times {10^{12}}$$
$$4.68 \times {10^9}$$