Electrochemistry Test

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Electrochemistry Test - 6

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Weekly Quiz Competition

Question 1
1 / -0

Corrosion of iron may be prevented by

A
covering the surface of iron with metallic nickel by electroplating

B
keeping the surface of iron wet

C
keeping a copper block in contact with iron

D
keeping iron immersed in brine
Question 2
1 / -0

Fuel cells are ________ that are designed to convert the energy of combustion of fuels like hydrogen, methane, methanol, etc. directly into_________.

A
Galvanic cells , electrical energy

B
Galvanic cells , thermal energy

C
Galvanic cells , hydraulic energy

D
Electrolytic cells , electrical energy

Solution

Fuel Cells are voltaic cells in which the reactants are continuously supplied to the electrodes where chemical energy due to combustion of gases such as H₂, CH₄,CO, etc are directly converted to electrical energy.
Question 3
1 / -0

The resistance of 0.01 N solution of an electrolyte was found to be 210 ohm at 298 K, using a conductivity cell of cell constant 0.66 cm⁻¹. The equivalent conductance of the solution is

A
3.14 mho⁻²cm²eq⁻¹

B
314.28 mho⁻¹cm²eq⁻¹

C
31.4 mho cm²eq⁻¹

D
314.28 mho cm²eq⁻¹
Question 4
1 / -0

In the primary batteries

A
the reaction occurs only once and after use it can be recharged and reused again

B
electrode reactions can be reversed by an external energy source and can be used again and again

C
the reaction is reversed periodically and after use over a period of time and so can be reused again

D
the reaction occurs only once and after use over a period of time battery becomes dead and cannot be reused again

Solution

In Primary batteries the electrode reactions cannot be reversed by an external energy source. so they are not chargeable.
Question 5
1 / -0

Same amount of electric current is passed through solutions AgNO₃ and HCl. If 1.08 g of silver is obtained in the first case, the volume of hydrogen liberated at STP in the second case is

A
112 L

B
112 mL

C
224 mL

D
1120 mL
Question 6
1 / -0

According to Faraday’s Second Law of Electrolysis, the amounts of different substances liberated by the same quantity of electricity passing through different electrolytic solution connected in series are proportional to

A
to their nuclear masses

B
to their atomic weight .

C
to their Atomic number

D
their chemical equivalent weights

Solution

Faradays II law statement - when same quantity of electricity is passed through different electrolytic solutions connected in series, the weights of the substances produced at the electrodes are directly proportional to their chemical equivalent weights
Question 7
1 / -0

When a rod of metallic lead was introduced into 0.01 M solution of Co (en)₂²⁺, it was found that 68% of the cobalt complex was reduced to Co (en)₃²⁺ by the lead. was -0.126 V.

of the reaction was

A
-1034 kJ

B
10.34 kJ

C
12.22 kJ

D
-12.22 kJ
Question 8
1 / -0

Why is KCl used in a salt bridge?

A
Because velocity of K⁺ is greater than Cl^-

B
Because velocity of K⁺ is less than Cl^-

C
Because velocities of K⁺ and Cl^- are nearly equal

D
Because KCl is soluble in water
Question 9
1 / -0

In an electrolysis of an aqueous solution of NaOH, 2.8 L of oxygen gas at STP was liberated at the anode. The volume of hydrogen gas at STP liberated at the cathode would be

A
2.8 L

B
5.6 L

C
11.2 L

D
22.4 L
Question 10
1 / -0

Which of the following statements is correct about an electrolytic cell?

A
It is a device which converts chemical energy into electrical energy.

B
The redox reaction in this case is spontaneous.

C
Electrons are supplied by external battery.

D
In this case, anode is negative and cathode is positive.
Question 11
1 / -0

On passing electric current, the quantity of deposition of a metal on cathode depends on the

A
shape of electrodes

B
size of electrodes

C
concentration of electrolytic solution

D
quantity of electric charge that passes through the solution
Question 12
1 / -0

Calculate the mass of copper that will be deposited at the cathode in the electrolysis of a 0.2 M solution of copper sulphate when quantity of electricity equal to that required to liberate 2.24 L of hydrogen at NTP from a 0.1 M aqueous sulphuric acid is passed. (Atomic mass of Cu = 63.5 u)

A
63.5 g

B
6.35 g

C
635 g

D
0.635 g
Question 13
1 / -0

Consider the cell:

Cd (s) | Cd²⁺ (1.0 M) || Cu²⁺ (1.0 M) | Cu (s)

If we want to make a cell with a more positive voltage using the same substances, we should

A
increase conc. of both the Cd²⁺ and Cu²⁺ to 2.00 M

B
increase conc. of only Cd²⁺ to 2.00 M

C
decrease conc. of both the Cd²⁺ and Cu²⁺ to 0.10 M

D
decrease conc. of only Cd²⁺ to 0.100 M
Question 14
1 / -0

If four moles of electrons are transferred from anode to cathode in an experiment on electrolysis of water, the total volume of the two gases produced at STP will be

A
22.4 L

B
72.6 L

C
67.2 L

D
89.4 L
Question 15
1 / -0

In an electrolytic cell, which of the following statements is not true?

A
Cathode is the negative terminal.

B
Cathode is the positive terminal.

C
Reduction occurs at the cathode.

D
Oxidation occurs at the anode.
Question 16
1 / -0

Salts of A (atomic weight 7), B (atomic weight 27) and C (atomic weight 24) were electrolysed under identical conditions using the same quantity of electricity. It was found that when 2.1 g of A was deposited, the weights of B and C deposited were 2.7 g and 3.6 g, respectively. The respective valencies of A, B and C are

A
2, 3 and 2

B
3, 1 and 3

C
6, 2 and 3

D
2, 3 and 1
Question 17
1 / -0

Which of the following compounds is prepared on a large scale by the electrolysis of NaCl?

A
Na₂CO₃

B
NaOH

C
NaHCO₃

D
NaOCl
Question 18
1 / -0

Which of the following solutions is used as an anti-rusting solution?

A
Na₂SO₄

B
Na₃PO₄

C
Na₃BO₃

D
Na₂S
Question 19
1 / -0

A secondary cell after use can be ________ by passing current through it in the ________ so that it can be used again.

A
recharged , same direction

B
recharged, opposite direction

C
charged , opposite direction

D
charged, same direction

Solution

Secondary cells are storage cells which can be recharged and reused again and again.
Question 20
1 / -0

Which of the following statements regarding dilution of an electrolytic solution is correct?

A
Both conductivity and molar conductivity increase.

B
Both conductivity and molar conductivity decrease.

C
Conductivity decreases and molar conductivity increases.

D
Conductivity increases and molar conductivity decreases.
Question 21
1 / -0

In corrosion, a metal is ______ of electrons which --------- to form oxides and hydroxides.

A
oxidized by loss, reduces oxygen

B
oxidized by gain, reduces moisture

C
reduced by loss, oxidises oxygen

D
oxidised by gain , reduces metal ion

Solution

During corrosion , Metals is oxidized by loss of electrons to metal ions and free electrons. The free electrons reduce the oxygen often times forming oxides and hydroxides .
Question 22
1 / -0

A solution containing one mole per litre of each Cu(NO₃)₂, AgNO₃, Hg₂(NO₃)₂ and Mg(NO₃)₂, is electrolysed by using inert electrodes. The values of standard electrode potentials in volts are Ag/Ag⁺ = +0.80, 2Hg/Hg₂²⁺ = +0.79, Cu/Cu²⁺ = +0.34, Mg/Mg²⁺ = -2.37. With increasing voltage, the correct sequence of deposition of metals on the cathode will be

A
Ag, Hg, Cu and Mg

B
Mg, Cu, Hg and Ag

C
Ag, Hg and Cu

D
Cu, Hg and Ag
Question 23
1 / -0

When electric current is passed through a cell having an electrolyte, the cations move towards the cathode and the anions towards the anode. If cathode is pulled out of the solution, then

A
the cations and anions will move towards the anode

B
the cations will start moving towards the anode, while the anions will stop moving

C
the anions will continue to move towards the anode and the cations will stop moving.

D
the cations and anions will start moving randomly.
Question 24
1 / -0

How many hours does it take to reduce 3 mol of Fe³⁺ to Fe²⁺ with 2.0 A current? [F = 96500 C]

A
39.15 hours

B
40.21 hours

C
50.21 hours

D
49.15 hours
Question 25
1 / -0

Which of the following metals forms a protective layer of oxide to prevent corrosion?

A
Cu

B
Ag

C
Au

D
Al

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Electrochemistry Test - 6

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Question 1

covering the surface of iron with metallic nickel by electroplating

keeping the surface of iron wet

keeping a copper block in contact with iron

keeping iron immersed in brine

Question 2

Galvanic cells , electrical energy

Galvanic cells , thermal energy

Galvanic cells , hydraulic energy

Electrolytic cells , electrical energy

Solution

Question 3

3.14 mho−2cm2eq−1

314.28 mho−1cm2eq−1

31.4 mho cm2eq−1

314.28 mho cm2eq−1

Question 4

the reaction occurs only once and after use it can be recharged and reused again

electrode reactions can be reversed by an external energy source and can be used again and again

the reaction is reversed periodically and after use over a period of time and so can be reused again

the reaction occurs only once and after use over a period of time battery becomes dead and cannot be reused again

Solution

Question 5

112 L

112 mL

224 mL

1120 mL

Question 6

to their nuclear masses

to their atomic weight .

to their Atomic number

their chemical equivalent weights

Solution

Question 7

-1034 kJ

10.34 kJ

12.22 kJ

-12.22 kJ

Question 8

Because velocity of K+ is greater than Cl-

Because velocity of K+ is less than Cl-

Because velocities of K+ and Cl- are nearly equal

Because KCl is soluble in water

Question 9

2.8 L

5.6 L

11.2 L

22.4 L

Question 10

It is a device which converts chemical energy into electrical energy.

The redox reaction in this case is spontaneous.

Electrons are supplied by external battery.

In this case, anode is negative and cathode is positive.

Question 11

shape of electrodes

size of electrodes

concentration of electrolytic solution

quantity of electric charge that passes through the solution

Question 12

63.5 g

6.35 g

635 g

0.635 g

Question 13

increase conc. of both the Cd2+ and Cu2+ to 2.00 M

increase conc. of only Cd2+ to 2.00 M

decrease conc. of both the Cd2+ and Cu2+ to 0.10 M

decrease conc. of only Cd2+ to 0.100 M

Question 14

22.4 L

72.6 L

67.2 L

3.14 mho⁻²cm²eq⁻¹

314.28 mho⁻¹cm²eq⁻¹

31.4 mho cm²eq⁻¹

314.28 mho cm²eq⁻¹

Because velocity of K⁺ is greater than Cl^-

Because velocity of K⁺ is less than Cl^-

Because velocities of K⁺ and Cl^- are nearly equal

increase conc. of both the Cd²⁺ and Cu²⁺ to 2.00 M

increase conc. of only Cd²⁺ to 2.00 M

decrease conc. of both the Cd²⁺ and Cu²⁺ to 0.10 M

decrease conc. of only Cd²⁺ to 0.100 M

Na₂CO₃

NaHCO₃

Na₂SO₄

Na₃PO₄

Na₃BO₃

Na₂S