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Test: Electrolysis & Faraday's Laws

32 Questions MCQ Test Topic-wise MCQ Tests for NEET | Test: Electrolysis & Faraday's Laws

Description

Attempt Test: Electrolysis & Faraday's Laws | 32 questions in 45 minutes | Mock test for NEET preparation | Free important questions MCQ to study Topic-wise MCQ Tests for NEET for NEET Exam | Download free PDF with solutions

QUESTION: 1

Only One Option Correct Type

This section contains 16 multiple choice questions. Each question has four choices (a), (b), (c) and (d), out of which ONLY ONE is correct

Q.

During the electrolysis of aqueous Zn(NO₃)₂solution

A.
Zn plates out at the cathode
B.
Zn plates out at the anode
C.
H₂ gas is evolved at the anode
D.
O₂ gas is evolved at the anode

Solution:

In preference to reduction of Zn²⁺ at cathode, O^2- (aq) is oxidised to O₂ at anode.

QUESTION: 2

Schematic diagram of an electrolytic cell is

A.
B.
C.
D.
None of these is the correct presentation

Solution:

In electrolytic cell,
Cation moves to cathode and anion moves to anode.

Electrons move anode to cathode.

QUESTION: 3

The metal that can not be obtained by electrolysis of an aqueous solution of its salt is

[JEE Main 2014]

A.
Ag
B.
Ca
C.
Cu
D.
Cr

Solution:

In electro chemical series (ECS),

thus, Ca²⁺ ion is not reduced to C a instead, H₂O is reduce d to H₂.

Ag, Cu and Cr are below H in ECS (E°_reduction > 0), thus they are reduced to metals on electrolysis.

Note In ECS, Ca, H, Cr, Cu elements lying above H are better reducing agents thus are easily oxidised.

QUESTION: 4

When during electrolysis of a solution of AgNO₃ ,9650 C of charge pass through the electroplating bath,the mass of silver deposited on the cathode will be

A.
1.08 g
B.
10.8 g
C.
12.6 g
D.
1.8 g

Solution:

QUESTION: 5

Refining of impure metal is done by electrolysis using impure metal as anode.Select the correct statement about this refining.

A.
E^°_cellof the net reaction is zero
B.
metal to be refined is dissolved in the solution and deposited at the cathode.
C.
Both (a) and (b)
D.
None of the above

Solution:

When impure metal (M) is anode and pure metal is made cathode, then

Thus, impure metal from the anode is deposited at the cathode.

QUESTION: 6

W g of Ag is deposited at the cathode of one electrolytic cell due to passage of 1A of current for 1h.Time required for passage of current to deposit W g of Mg by the same value of current is

A.
9 h
B.
4.5 h
C.
1 h
D.
3.0 h

Solution:

QUESTION: 7

In the refining of silver by electrolytic method, current of 5A is passed for 2 h using 100 g of impure anode of silver (of 95% purity). Weight of silver anode after electrolysis is

A.
40.29 g
B.
59.71 g
C.
57.59 g
D.
42.41 g

Solution:

By Faraday 's first law of electrolysis

QUESTION: 8

In the electrorefining of metals, impure metal is

A.
cathode and oxidation taken place
B.
anode and oxidation takes place
C.
anode and reduction takes place
D.
cathode and reduction takes place

Solution:

Impure metal is made the anode and oxidation takes place

Cu²⁺ formed are reduced at cathode and thus, deposited there.

QUESTION: 9

In the electrosynthesis,potassium manganate (VII) is converted to manganese(IV) dioxide. By passage of 1F of electrolysis ,one mole of potassium manganate(VII) will form manganese dioxide.

A.
1.00 mol
B.
0.50 mol
C.
0.66 mol
D.
0.33 mol

Solution:

Manganate (VII) is MnO₄^- with ON of Mn = + 7
1 mole required 3F of electricity thus, 1 F will reduce only (1/3) mole MnO₄^- t o MnO₂.
Thus, MnO₂ formed = 0.33 mol.

QUESTION: 10

When Al₂O₃ is electrolysed ,cation and anions are discharged. For a given quantity of electricity,ratio of number of moles of Al and O₂ gas is

A.
1 : 1
B.
2 : 1
C.
2 : 3
D.
4 : 3

Solution:

When same quantity of electricity is passed, elements/gases are formed in the ratio of their equivalents
.

QUESTION: 11

1 Faraday of electricity is passed through the solution containing 1 mole each of AgNO₃, CuSO₄, AlCl₃and SiCl₄. Elements are discharged at the cathode.Number of moles of Ag, Cu,Al and Si formed will be in the ratio of

A.
1 : 1 : 1 : 1
B.
1 : 2 : 3 : 4
C.
6 : 4 : 3 : 1
D.
12 : 6 : 4 : 3

Solution:

(d)

QUESTION: 12

During electrolysis of acidified water ,O₂ gas is formed at the anode. To produce O₂ gas at the anode at the rate of 0.224 cc per second at STP,current passed is

A.
0.224 A
B.
2.24 A
C.
9.64 A
D.
3.86 A

Solution:

QUESTION: 13

A solution of copper(II) sulphate (VI) is electrolysed between copper electrodes by a currrent of 10.0 A for exactly 9650 s.Which remains unchanged?

A.
Molar concentration of solution
B.
Cathodic plate
C.
Anodic plate
D.
All of these

Solution:

0.5 mole of copper is dissolved from the anode. Thus, its mass decreases. 0.5 mole of copper from the anode is deposited at the cathode. Thus, its mass increases.
Thus, molar concentration of aqueous solution of CuSO₄ remains unchanged.

QUESTION: 14

A 300 mL solution of NaCl was electrolysed for 60.0 min. If the pH of the final solution was 12.24,average current used is

A.
1.40 A
B.
1.27 A
C.
0.70 A
D.
0.14 A

Solution:

QUESTION: 15

100 mL of a buffer of 1 M NH₃(aq) and 1 M NH₄⁺(aq) are placed in two volatic cells separately.A current of 1.5 A is passed through both cells for 20 min. If electrolysis of water only takes place

2H₂O +O₂ + 4e^- → 4OH^- (RHS

2H₂O → 4H^{+. + O₂}+ 4e^- (LHS)

then pH of the

A.
LHS half-cell will increase
B.
RHS half-cell will increase
C.
both half-cell will increase
D.
both half-cell will decrease

Solution:

In RHS, [NH₃] increases hence, pOH decreases
pH = 14 - pOH
Hence, pH of RHS increases.
In LHS, [NH₄⁺] increases, hence pOH increases and pH decreases.

QUESTION: 16

What product are formed during the electrolysis of a concentrated aqueous solution of sodium chloride using an electrolytic cell in which electrodes are separated by a porous pot?

I. Cl₂(g)
II. NaOH(aq)
III. H₂(g)
IV. NaClO(aq)
V. NaClO₃(aq)

Select the correct choice.

A.
I and II
B.
I , II and V
C.
I , IiI and V
D.
I , II and III

Solution:

Cl₂(g) is formed at anode and NaOH and H₂ are formed at cathode. Since, cathode and anode are separated. Hence. there is no reaction between the products formed at the cathode and anode.

Note: but these reaction do not occur

Note: NaCl is neutral pH = 7 initially. After electrolysis , NaOH is formed

Hence, solution become, basic pH >7

*Multiple options can be correct

QUESTION: 17

One or More than One Options Correct Type

This section contains 5 multiple type questions. Each question has 4 choices (a), (b), (c) and (d), out of which ONE or MORE THAN ONE are correct.

Select the correct point(s) of distinction between a volatic cell and electrolysis cell.

A.
a
B.
b
C.
c
D.
d

Solution:

(a.c.d) Regardlessvehether a cell is a volatic or an electrolysis cell, anode s the electrode at which oxidation takes place and cathode is the electrode at which reduction takes place. In electrochemical cell, Zn → Zn²⁺ + 2e^- .

It is losing electrons thus, anode is negative terminal. In electrolysis cell. cation migrates to cathode thus -ye terminal. anion migrates to anode thus +ve terminal.

*Multiple options can be correct

QUESTION: 18

In the electrolysis of aqueous sodium chloride solution, two types of reactions can take place at anode :

I. 2Cl^- (aq) → Cl₂(g) +2e^-

II. 2H₂O(l)g → O₂ (g) + 4H⁺(aq) + 4e^-

Select the correct statement(s) about these.

A.
Electrode potentials of I and II are quite similar
B.
I is favoured in higher (NaCl) and II is favoured in higher pH.
C.
Because of overvoltage ,Cl₂and not O₂ is formed
D.
Electrode potentials of I and II are different

Solution:

(c) Experrnent indicates that the applied voltage required is always greater than the voltage calculated from the standard E⁰_ox or E⁰_red. The additional voltage required is called overvoltage. Due to this, Cl₂ and not O₂ s formed. This, (c) 6 correct.

*Multiple options can be correct

QUESTION: 19

Select the correct statement(s) about electrolysis of aqueous CuSO₄solution.

A.
Anodic reaction is 2H₂O(l) → 4H⁺(aq) + O₂(g) + 4e-
B.
Cathodic reactions 2Cu²⁺ (aq) + 4e^- → 2Cu(s)
C.
Due to the deposition of Cu at the cathode,this is the basis of electroplating of copper
D.
Blue colour of the solution fades

Solution:

(a)

Oxidation takes place at anode - correct

2H₂O(l) →4H⁺ (aq) + O₂(g) + 4e^-

(b) Reduction take place at cathode - correct

since, E⁰_cell< 0, in electrolysis.

Cell reaction is spontaneous.

(c) Copper is deposited at the cathode, hence the meted to be electroplated (say Fe), should be made cathode - correct (d) Since. Cu²⁺(aq)- (blue) is reduced Cu(s), hence blue colour fades - correct.

*Multiple options can be correct

QUESTION: 20

Select the correct observation about electrolysis.

A.
Electric current is used to drive a non-spontaneous reaction
B.
E_cell is positive and ΔG is negative
C.
Cations and anions are discharged at the cathode and anode respectively
D.
Overvoltage is responsible that a particular reaction takes place

Solution:

Thus, electric current is used to carry out a non-spontaneous reaction.
Thus. (a) is correct.
(b) Since reactions are reverse of electrochemical cell, hence

thus, (b) is incorrect

(d) some additional voltage called overvoltage is set up and thus other reactions also take place. thus correct

*Multiple options can be correct

QUESTION: 21

Which pair of electrolysis could be distinguished by the products of electrolysis using inert electrodes?

A.
1 M CuSO₄,1 M CuCl₂
B.
1 M KCl ,1 M KI
C.
1 M AgNO₃,1 M CuSO₄
D.
1 M CuBr₂ , 1 M NiBr₂

Solution:

a(Cu So₄ and CuCl₂ changes to Cu and solution becomes colourless

(b) KCl changes to Cl₂ (yellow)
KI changes to I₂ (voilet)

Thus, distinguished.

CuSo₄ (blue) changes to colourless

(d) CuBr₂ (blue) both changes to colourles.

NiBr₂ (Blue)

QUESTION: 22

Comprehension Type

This section contains a passage describing theory, experiments, data, etc. Two questions related to the paragraph have been given. Each question has only one correct answer out of the given 4 options (a), (b), (c) and (d)

Passage I

A constant current of 30 A is passed through an aqueous solution of NaCl for a time of 1.00 h.

Thus NaOH formed due to electrolysis is

A.
40.2 g
B.
44.8 g
C.
31.1 g
D.
22.4 g

Solution:

The correct answer is option B
Formula used : W=ZIt
where Z is the equivalent mass of the deposit divided by 1 Faraday charge i.e. 96500 C.

Now, W= [(40/{+1})/96500] x 30 x 3600s

≈ 44.8 g

QUESTION: 23

Passage I

A constant current of 30 A is passed through an aqueous solution of NaCl for a time of 1.00 h.

Thus Cl₂ formed under STP condition is

A.
12.54 L
B.
11.22 L
C.
22.40 L
D.
5.60 L

Solution:

At anode 2Cl^- —-±>Cl₂+2e^-
At cathode 2Na⁺ +2e^- ——-> 2Na.
So 2 Faraday of electricity is required to liberate 1 mole = 22.4 liters of Cl₂ at STP.
Amount of current passed
= 30 x 60 x 60=108000 coulombs.
So 108000 coulombs will liberate =108000/(96500 x2) = 0.5596 moles Cl₂.
No.of liters of Chlorine liberated at STP
= 0.5596 x 22.4 = 12.53 liters.

QUESTION: 24

Passage II

In hydrogen economy fuel-cell,anodic and cathodic reactions are

Anodic

H₂+2OH^- → 2H₂O + 2e^-

Cathodic

O₂+2H₂O + 2e^- → 4OH^-

67.2 L H₂ at STP react in 15 min.Entire current is used for electro deposition of copper from copper(II) sulphate solution. Average current produced in fuel cell is

A.
610.00 A
B.
620.00 A
C.
617.8 A
D.
643.3 A

Solution:

QUESTION: 25

Passage II

In hydrogen economy fuel-cell,anodic and cathodic reactions are

Anodic

H₂+2OH^- → 2H₂O + 2e^-

Cathodic

O₂+2H₂O + 2e^- → 4OH^-

67.2 L H₂ at STP react in 15 min.Entire current is used for electro deposition of copper from copper(II) sulphate solution. Copper deposited would be

A.
1.0 mol
B.
2.0 mol
C.
3.0 mol
D.
4.0 mol

Solution:

*Answer can only contain numeric values

QUESTION: 26

One Integer Value Correct Type

This section contains 6 questions, when worked out will result in an integer value from 0 to 9 (both inclusive)

Mⁿ⁺solution was electrolysed for 75 min by a current of 0.30 A. Mass of the metal M deposited at the cathode was 9.958 g.Mⁿ⁺contains 68 protons and 69 neutrons. What is the value of n?

Solution:

*Answer can only contain numeric values

QUESTION: 27

An electrochemical cell was based on the following reaction:

Mn(OH)₂(s) + H₂O₂(aq) → MnO₂(s) + 2H₂O (e)

During the opeartion of this for 1 min, 0.135 g of MnO₂ was produced. What is the average electric current (in ampere ) produced by the cell?

Solution:

*Answer can only contain numeric values

QUESTION: 28

In a fuel cell, following reactions takes place and electricity is produced.

Anodic

H₂+2OH^- → 2H₂O + 2e^-

Cathodic

O₂+2H₂O + 4e^- → 4OH^-

If 100.8 L of H₂ at STP reacts in 96500 s,what is the average current produced (in ampere)?

Solution:

*Answer can only contain numeric values

QUESTION: 29

How long (in minutes ) a current of 1.56 A has to be passed through a solution of AgNO₃ to coat a metal surface of 80 cm² with a 0.010 mm thick layer? Density of silver is 10.5 g cm^-3.

Solution:

*Answer can only contain numeric values

QUESTION: 30

A fully charged battery contains 500 mL of 5.00 M H₂SO₄. What is the concentration of H₂SO₄in the battery after 6.0 A of current is drawn from the battery for 13.40 h?

Solution:

*Answer can only contain numeric values

QUESTION: 31

A hydrogen-oxygen fuel cell opeartes on the simple reaction:

If the cell is designed to produce 1.46A of current and if the H₂ is contained in a 1.0 L tank at 2.00 atm pressure at 298K, how long can the fuel cell operate(in hour) before the H₂ runs out.(Assume unlimited supply of oxygen)

Solution:

QUESTION: 32

Matching List Type

Choices for the correct combination of elements from Column I and Column II are given as options (a), (b), (c) and (d), out of which one is correct

Four electrolytic cells containing solution of ZnSO₄, AgNO₃, CuSO₄ and dil. H₂SO₄ are connected in series. A steady current of 1.5 A was passed through them until 77 mL of O₂ gas at STP is formed in anode compartment of H₂SO₄ solution. Match the different elements/gas formed In Column I with their values in Column II and select the answer from the codes given below. (Cu = 63.5, Zn = 65, Ag = 108, S = 32, H = 1, 0 = 16)