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CBSE Questions for Class 12 Engineering Chemistry Electrochemistry Quiz 12 - MCQExams.com

An aqueous solution of X is added slowly to an aqueous solution of Y as shown in List I. The variation in conductivity of theses reactions is given in List II. Match List I with List II and select the correct using the code given below the lists:
List-A
List-B
(P) (C2H5)3NX+CH2COOHY
(1) Conductivity decreases and then increases
(Q) KI(0.1M)X+AgNO3(0.01M)Y
(2) Conductivity decreases and then does not change much
(R) CH2COOX+KOHY(3) Conductivity increases and then does not change much
(S) NaOHX+HIY(4) Conductivity does not change much and then increases.

  • 3, 4, 2, 1
  • 4, 3, 2, 1
  • 2, 3, 4, 1
  • 1, 4, 3, 2
Zn|Zn2+(c1)||Zn2+(c2)|Zn. For this cell ΔG is negative if:
  • c1=c2
  • c1>c2
  • c2>c1
  • None
The tarnishing of silver ornaments in atmosphere is due to:
  • Ag2O
  • Ag2S
  • Ag2CO3
  • Ag2SO4
The electrical conductivity of a solution serves as a means of determining the end point in a chemical reaction, involved in the titration of acids, bases, or precipitation. Which of the following conductometric titration represent the curve of HCl vs NaOH :
x-axis Volume of alkali added
y-axis  Conductivity
ΔG for the following reaction is:
4A1+3O2+6H2O+4OH4A1(OH)4
Ecell=2.73V
ΔfG(OH)=157kJmol1
ΔfG(H2O)=237kJmol1
  • 3.16×103kJmol1
  • 0.79×103kJmol1
  • 0.263×103kJmol1
  • +0.263×103kJmol1
For the electrolytic production of NaClO4 from NaClO3 according to the reaction NaClO3+H2ONaClO4+H2. How many faradays of electricity would be required to produce 0.5 mole of NaClO4 ?
  • 1
  • 2
  • 3
  • 1.5
Chromium plating can involve the electrolysis of an electrolyte of an acidified mixture of chromic acid and chromium sulphate. If during electrolysis the article being plated increases in mass by 2.6 g and 0.6dm3 of oxygen are evolved at an inert anode, the oxidation state of chromiumions being discharged must be : (assuming atomic weight of Cr = 52 and 1 mole of gas at room temperature and pressure occupies a volume of 24 dm3)
  • 1
  • 0
  • +1
  • +2
The EforCu2+/Cu,Cu/Cu,Cu2+/Cu, are 0.15 V, 0.50 V, and 0.325 V, respectively. The redox cell showing redox reaction 2Cu+,Cu2++Cu is made. E of this cell reaction and ΔG may be :
  • E=0.175VorE=0.350V
  • n=1or 2
  • ΔG=33.775kJ
  • All of these
The passage of 1.5 Faradays of electricity corresponds to the flow of how many electrons?
  • 6×1023
  • 9×1023
  • 12×1023
  • 3×1023
What happens when lead storage battery is discharged?
  • SO2 is evolved
  • Lead sulphate is consumed
  • Lead is formed
  • H2SO4 is consumed
A process in which a thin film of a metal like gold, silver, etc., is deposited on another metallic article with the help of electricity.
  • Electrorefining
  • Electroplating
  • Electrochemical process
  • Galvanization
Select the correct statement.
  • Faraday represents 96500 coulombs per second.
  • Coulomb represents one ampere for 1/2 second.
  • Coulomb represents 1/2 ampere for 1 second.
  • Faraday represents charge of one mole electron.
The rusting of iron takes place as follows:
2H+2e+12O2H2O(l);E=+1.23V
Fe2+(aq)+2eFe(s);E=0.44V
Calculate ΔG for the net process.
  • 322kJ mol1
  • 152kJ mol1
  • 76kJ mol1
  • 161kJ mol1

Separating the components of a homogeneous mixture using electricity is called:

  • electrification
  • electrolysis
  • electrolyte
  • electromagnetisation
1 Faraday can be defined as : 
  • the magnitude of the charge of 1 mole of electrons
  • the magnitude of the electric dipole
  • a fundamental constant of nature equal to 6.63×1034 J s/photon
  • a constant that accounts for the existence of ions in solution
  • the assignment of charges to individual atoms
What is the charge on an individual electron, if one F is equivalent to 96,487 C/mole?
  • 5.76×1028C/e
  • 6.022×1023C/e
  • 1.6×1019C/e
  • 1.6×1019C/e
About an electrolyte cell, which of the following is true?
  • An electric current causes an otherwise non-spontaneous chemical reaction to occur
  • Reduction occurs at the anode
  • A spontaneous electrochemical reaction produces an electric current
  • The electrode to which electrons flow is where oxidation occurs
  • None of the above
For a reaction, where the ΔGo=553.91kJ and 2 electrons are transferred, what will be the  Eocellof the reaction?
  • 2.87V
  • 0.00287V
  • 0.00287V
  • 2.87V
Assertion : A voltaic cell spontaneously converts chemical energy into electrical energy.

Reason : A voltaic cell needs an externally applied current to work.
  • Both Assertion and Reason are true and Reason is the correct explanation of Assertion
  • Both Assertion and Reason are true but Reason is not the correct explanation of Assertion
  • Assertion is true but Reason is false
  • Assertion is false but Reason is true
  • Both Assertion and Reason are false
The below reaction is the gold-plating process reaction.
            Au3+(aq)+3eAu(s)
If 0.600g of Au is plated onto a metal, how many coulombs are used?
  • 299C
  • 868C
  • 2,990C
  • 8,680C
In an electrochemical cell, reduction takes place at anode          BECAUSE           oxidation always takes place at the cathode.
  • F, F
  • F,T
  • T,T
  • T,F
How many Faraday (F) are required for the reduction of 1 mole of Ni2+ to Ni(s)?
  • 1F
  • 2F
  • 96,487F
  • 6.022×1023F
Energy is required for the electrolysis of water because H2O has less chemical potential energy than the products formed, H2 and O2.
  • True
  • False
Which of these processes could be associated with the following reaction.
2H2O2H2+O2.
i. Electrolysis
ii. Neutralization
iii. Decomposition
  • i only
  • iii only
  • i and iii only
  • i and ii only
  • ii and iii only
A salt bridge :
  • is not used in a galvanic cell
  • completes the circuit
  • increases the rate of reaction
  • provides an easy handle to carry the cell
  • None of these 
The standard Gibbs free energy change (G in kJ mol1), in a Daniel cell (Ecell=1.1V), when 2 moles of Zn(s) is oxidized at 298 K, is closest to:
  • 212.3
  • 106.2
  • 424.6
  • 53.1
Which one of the following species has maximum conductance in their aqueous solutions?
  • K2PtCl6
  • PtCl42NH3
  • PtCl43NH3
  • PtCl45NH3
The approximate time duration in hours to electroplate 30 g of calcium from molten calcium chloride using a current of 5 amp is :
[Atomic mass of Ca=40]
  • 8
  • 80
  • 10
  • 16
Consider a galvanic cell using solid Cu and Fe metals with their corresponding solutions.
What is the Ecell?
Standard Potential (V)Reduction Half-Reaction
2.87F2(g)+2e2F(aq)
1.51MnO4(aq)+8H+(aq)+5eMn2+(aq)+4H2O(l)
1.36Cl2(aq)+3e2Cl(aq)
1.33Cr2O27(aq)+14H+(aq)+6e2Cr3+(aq)+7H2O(l)
1.23O2(g)+4H+(aq)+4e2H2O(l)
1.06Br2(l)+2e2Br(aq)
0.96NO3(aq)+4H+(aq)+3eNO(g)+H2O(l)
0.80Ag+(aq)+eAg(s)$
0.77Fe3+(aq)+eFe2+(aq)
0.68O2(g)+2H+(aq)+2eH2O2(aq)
0.59MnO4(aq)+2H2O(l)+3eMnO2(s)+4OH(aq)
0.54I2(s)+2e2I(aq)
0.40O2(g)+2H2O(l)+4e4OH(aq)
0.34Cu2+(aq)+2eCu(s)
02H+(aq)+2eH2(g)
0.28Ni2+(aq)+2eNi(s)
0.44Fe2+(aq)+2eFe(s)
0.76Zn2+(aq)+2eZn(s)
0.832H2O(l)+2eH2(g)+2OH(aq)
1.66Al3+(aq)+3eAl(s)
2.71Na+(aq)+eNa(s)
3.05Li+(aq)+eLi(s)
  • 0.78V
  • 0.10V
  • 0.78V
  • 0.10V
A positive cell potential tells you ________.
  • the reaction is not spontaneous
  • the reaction is spontaneous
  • the reaction will not occur without intervention
  • ΔG is negative
  • both the reaction is spontaneous and ΔG is negative
Consider the table of standard reduction potentials shown below.
Half-reactionE
Cl2+2e2Cl1.36 V
O2+4H++4e2H2O1.23 V
2H2O+2eH2+2OH0.83 V
Rb++eRb2.93 V
Use the information from the table and your knowledge of electrochemistry to predict the CORRECT net ionic equation for the reaction that will occur when an aqueous solution of rubidium chloride undergoes electrolysis.
  • 2Rb++2Cl2Rb+Cl2
  • 2H2O2H2+O2
  • H2+2OH+2Rb+2Rb+2H2O
  • 4Cl+O2+4H+2H2O+2Cl2
A steady current of 10.0 Amps is passed through a nickel production cell of 15 minutes.
Which of the following is the correct expression for calculating the number of grams of nickel produced?
Note:
1 faraday=96,500 Coulombs
The electroytic cell involves the following half-reaction:
Ni2+(aq)+2eNi(s)
  • (10.0)(15)(96,500)(59)(60)g
  • (10.0)(15)(59)(60)(96,500)g
  • (10.0)(15)(60)(59)(96,500)(2)g
  • (96,500)(59)(10)(15)(60)(2)g
How many coulombs of electricity are required for the oxidation of one mole of water to dioxygen?
  • 9.65×104C
  • 1.93×104C
  • 1.93×105C
  • 19.3×105C
Electrolysis of dilute aqueous NaCl solution was carried out by passing 10 mA current. The time required to liberate 0.01 moles of H2 gas at the cathode is
  • 9.65×104s
  • 19.3×104s
  • 28.95×104s
  • 38.6×104s
A 250.0 ml sample of a 0.20 M Cr3+ is electrolysed with a current of 96.5 A. If the remaining [Cr3+] is 0.1 M the duration of process is ?
  • 25 sec
  • 50 sec
  • 100 sec
  • 75 sec
Two half-cells have potentials 0.44 and 0.799 volt respectively. These two are coupled to make a galvanic cell. Which of the following will be true?
  • Electrode of half-cell potential 0.44 V will act as anode
  • Electrode of half-cell potential 0.44 V will act as cathode
  • Electrode of half-cell potential 0.799 V will act as anode
  • Electrode of half-cell potential 0.44 V will act as a positive terminal
W g of Ag is deposited at the cathode of one electrolytic cell due to the passage of 1A of current for 1h. The time required for passage of current to deposit W g of Mg by the same value of current is:
  • 3.0h
  • 9h
  • 2.5h
  • 1h
The reaction taking place in the cell Pt|H2(g)1 atm|HCl(1.0 M)|AgCl|Ag is:
  • AgCl+(1/2)H2Ag+H++Cl
  • Ag+H++ClAgCl+(1/2)H2
  • 2Ag++H22Ag+2H+
  • 2Ag+2H+2Ag++H2
An electrolysis of a oxytungsten complex ion using 1.10 A for 40 min produces 0.838 g of tungsten. What is the charge of tungsten in the material? (Atomic weight: W=184)
  • 6
  • 3
  • 5
  • 1
If 0.50 L of a 0.60 M SnSO4 solution is electrolysed for a period of 30.0 min using a current of 4.60 A. If in electrodes are used, what is the final concentration of Sn2+ remaining in the solution? [at.wt. of Sn=119]
  • 0.257 M
  • 0.544 M
  • 0.189 M
  • 0.514 M
Calculate the potential of an indicator electrode, which originally contained 0.1M MnO4 and 1.72M H+, and was treated with Fe2+, necessary to reduce 90% of KMnO4 to Mn2+

Given: [E0MnO4/Mn+2=1.51V]
  • 1.4V
  • 1.5V
  • 1.6V
  • 1.3V
The density of copper is 8gm/cc. Number of coulumbs required to plate an area of 10cm×10cm on both sides to a thickness of 102cm using CuSO4 solution as electrolyte is:
  • 24,250
  • 48,124
  • 96,500
  • 10,000
Consider the following half-cell reactions and associated standard half-cell potentials and determine the maximum voltage that can be obtained by combination resulting in spontaneous processes:
AuBr4(aq)+3eAu(s)+4Br(aq);E=0.86 V
Eu3+(aq)+eEu2+(aq);E=0.43 V
Sn2+(aq)+2eSn(s);E=0.14 V
IO(aq)+H2O(l)+2eI(aq)+2OH(aq);E=+0.49 V
  • +0.72
  • +1.54
  • +1.00
  • +1.35
Consider the half-cell reduction reactions :
Mn2++2eMn,Eo=1.18 V
Mn2+2n3++e,Eo=1.51 V
The Eo for the reaction 3Mn2+Mn0+2Mn3+ and possibility of the forward reaction are respectively:
  • -4.18 V and yes
  • +0.33 V and yes
  • +2.69 V and no
  • -2.69 V and no
A current of i ampere was passed for t sec, through three calls P,Q and T connected in series. These contain respectively silver nitrate, mercuric nitrate, and mercurous nitrate. At the cathode of the cell P,0.216g of Ag was deposited. The weights of mercury deposited in the cathode of Q and R respectively are: (at wt. of Hg=200.59)
  • 0.4012 and 0.8024g
  • 0.4012 and 0.2006g
  • 0.2006 and 0.4012g
  • 0.1003 and 0.2006g
The heat of combustion of ethanol in a bomb calorimeter is 670.48Kcal mol1 at 25oC. What is ΔE at 25oC for the reaction?
  • -269.24 kcal
  • -469.28 kcal
  • -671.07 kcal
  • +770.48 kcal
Electrolysis can be used to determine atomic masses. A current of 0.550 A deposits 0.55. If a certain metal in 100 minutes. Calculate the atomic mass of the metal if eq. mass mole mass /3.
  • 100
  • 45.0
  • 48.25
  • 144.75
Consider an electrochemical cell in which the following reaction occurs and predict which changes will decreases the cell voltage:

Fe^{2+} (aq) + Ag^{+}(aq)\rightarrow Ag(s) + Fe^{3+}(aq)

(I) decreases the [Ag^{+}] (II) increases in [Fe^{3+}] (III) increase the amount of Ag
  • I only
  • II and III only
  • II only
  • I and II only
What will be \Delta H for the reaction; Ag(s)+\dfrac{1}{2}Hg_2Cl_2(s)\rightarrow AgCl(s)+Hg(l) at 25^0c, if this reaction can be conducted in a cell for which the emf = 0.0455 volt at this temperature with temperature coefficient 3.389\times10^{-4} volt\, deg^{-1}?
  • +1280 cal
  • +640 cal
  • -1280 cal
  • -640 cal
{ E }^{ 0 } value of Mg/{ Mg }^{ +2 } is +2.37 V of Zn/{ Zn }^{ +2 } is +0.76 V and that of Fe/{ Fe}^{ +2 } is +0.44 V, which of the following statements is correct?
  • Zinc will reduce { Mg }^{ +2 }
  • Zn will reduce { Fe }^{ +2 }
  • Mg oxidizes Fe
  • Zn oxidizes Fe
0:0:1


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