3195 + Interview Questions in ELECTROCHEMISTRY IN GENERAL AWARENESS Page 23 InterviewSolution

1101.	The standard H electrode is written asA. `Pt \|H_(2)\| H^(+) (a = 1)`B. `Pt\|H_(2)\|H^(+)`C. `H^(+) (a = 1) \| H_(2 (g)) \|Pt`D. `H^(+) (a = 1) \| H_(2 (s)) \| Pt`
Answer» Correct Answer - C This is representation of standard hydrogen electrode .

Discussion

1102.	For the cell reaction, `underset((C_(1)))(Cu^(2+)) (aq.)+Zn(s) rarr underset((C_(2)))(Zn^(2+))(aq.)+Cu(s)` the change in free energy `(Delta G)` at a given temperature is a function of:A. `ln C_(1)`B. `ln ((C_(2))/(C_(1)))`C. `ln (C_(1)+C_(2))`D. `ln C_(2)`
Answer» Correct Answer - B

Discussion

1103.	Standard electrode potential of an electrode is :A. Intensive propertyB. Extensive propertyC. Isothermal propertyD. Isobaric property
Answer» Correct Answer - A `E^(@)` is mass independent.

Discussion

1104.	A gas X at 1 atm is bubbles through a solution containing a mixture of 1M `Y^(-) and MZ^(-)` at `25^(@)C` If the reduction potential of ZgtYgtX, then,A. Y will oxidize X and not ZB. Y will oxidize Z and not XC. Y will oxidize both X and ZD. Y will reduce both X and Z
Answer» Correct Answer - A The given order of reduction potential is `Z gt Y gt X`. A spontaneous reaction will have the following characteristics Z reduced and Y oxidized, Z reduced and X oxidised, Y reduced and X oxidized. Hence, Y will oxidize X and not Z.

Discussion

1105.	A gas X at 1 atm pressure is bubbled through a solution containing a mixture of `1 M Y^(-)` and `1 MZ^(-)` at `25^(@)C`. If the reduction potential of `Z gt Ygt X`, thenA. Y will oxidise X and not ZB. Y will oxidise Z and not XC. Y will oxidise both Z and X.D. Y will oxidise both X and Z.
Answer» Correct Answer - A (a) is the correct answer.

Discussion

1106.	A gas X at 1 atm is bubbled through a solution containing a mixture of `1 M Y^(-)` and `1 M Z^(-)` at `25^(@)C`. If the order of reduction potentials is `Z gt Y gt X`, thenA. Y will oxidise X and not ZB. Y will oxidise Z and not XC. Y will oxidise both X and ZD. Y will reduce both X and Z
Answer» Correct Answer - A The tendency to gain electron is in the order `Z gt Y gt X` Thus , `Y + e to Y^(-) and X to X^(+) + e `

Discussion

1107.	The standard reduction potential values of three metallic cation `X, Y, Z` are `0.52, -3.03` and `-1.18 V` respectively. The order of reducing power to the corresponding metals is:A. `Y gt Z gt X`B. `X gt Y gt Z`C. `Z gt Y gt X`D. `Z gt X gt Y`
Answer» Correct Answer - A Given values are of `E_(RP)^(@) ` . Thus , `E_(RP)^(@)` order is `Y gt Z gt X` , more is `E_(OP)^(@)` , more is the tendency to get oxidise and thus more is the reduction nature .

Discussion

1108.	The standard reduction potential of three metallic cations X,Y and Z are +0.52, -0.52, 3.03 and -1.18 V respectively. The order of reducing power is :A. `Y gt Z gt X`B. `X gt Y gt Z`C. `Z gt Y gt X`D. `Z gt X gt Y`
Answer» Correct Answer - A (a) is the correct answer.

Discussion

1109.	The emf of the cell, `Ni\|Ni^(2+)(1.0M)\|\|Ag^(+)(1.0M)\|Ag [E^(@)` for `Ni^(2+)//Ni =- 0.25` volt, `E^(@)` for `Ag^(+)//Ag = 0.80` volt] is given by : `[E^(@)` for `Ag^(+)//Ag = 0.80` volt]A. `-0.25 +0.80 = 0.55` voltB. `-0.25 -(+0.80) =- 1.05` voltC. `0 +0.80 -(-0.25)=+ 1.05` voltD. `-0.80 -(+0.25) =- 0.55` volt
Answer» Correct Answer - C `E_("cell")^(@)= E_("cathod")^(@)-E_("anode")^(@)=0.80 - (-0.25)= 1.05 V`

Discussion

1110.	When iron is rusted, it isA. reducedB. oxidisedC. evaporatedD. decomposed
Answer» Correct Answer - B Fe converts into `Fe_(2)O_(3).H_(2)O`. Thus Fe oxidised.

Discussion

1111.	The reduction potential of a hydrogen electrode at `pH 10` at `298K` is : `(p =1` atm)A. `0.51` voltB. 0 voltC. `-0.591` voltD. `0.059` volt
Answer» Correct Answer - C `2H^(+)+2e^(-)rarr H_(2) pH = 10, [H^(+)]= 10^(-10)` `E^(@)=0` `E_("red") = (0.0591)/(2) "log" ([H^(+)]^(2))/(P_(H_(2))(g)) = (0.0591)/(2)xx2log[10^(-10)]` `= (0.0591)/(2)xx2xx[-10]= -0.591 V`

Discussion

1112.	The standard reduction potential values of three metallic cation `X, Y, Z` are `0.52, -3.03` and `-1.18 V` respectively. The order of reducing power to the corresponding metals is:A. `Y gt Z gt X`B. `X gt Y gt Z`C. `Z gt Y gt X`D. `Z gt X gt Y`,
Answer» Correct Answer - A More is `E_(RP)^(@)`, more is the tendency to get reduced or more is the oxidizing power or lesser is reducing power. Thus Oxidizing power `= X^(+) gt Z^(+) gt Y^(+)` Reducing power `= Y gt Z gt X`

Discussion

1113.	Given: (i) `Cu^(2+)+2e^(-) rarr Cu, E^(@) = 0.337 V` (ii) `Cu^(2+)+e^(-) rarr Cu^(+), E^(@) = 0.153 V` Electrode potential, `E^(@)` for the reaction, `Cu^(+)+e^(-) rarr Cu`, will beA. 0.52 VB. 0.90 VC. 0.30 VD. 0.38 V
Answer» Correct Answer - A (a) `DeltaG^(@)=-nFE^(@)` For reaction, `Cu^(2+)+2e^(-) to Cu, ` …(i) `DeltaG^(@)=-2xxFxx0.337` For reaction, `Cu^(+) to Cu^(2+)+e^(-)`, ….(ii) `DeltaG^(@)=-1xxFxx(-0.153)` `=+0.153 F` Adding Eqs. (i) and (ii) , we get `Cu^(+)+e^(-) to Cu, DeltaG^(@)=-0.521 F` `DeltaG^(@)=-nFE^(@)` `:. -0.521 F=-nFE^(@)` `:. E^(@)=0.52 V`

Discussion

1114.	Given: (i) `Cu^(2+)+2e^(-) rarr Cu, E^(@) = 0.337 V` (ii) `Cu^(2+)+e^(-) rarr Cu^(+), E^(@) = 0.153 V` Electrode potential, `E^(@)` for the reaction, `Cu^(+)+e^(-) rarr Cu`, will be
Answer» `DeltaG^(@)=-nFE_(cell)^(@)` `DeltaG_(3)^(@)=DeltaG_(1)^(@)-DeltaG_(2)^(@)` `(-n_(3)FE_(3)^(@))=(-n_(1)FE_(1)^(@))-(-n_(2)FE_(2)^(@))` or `" " (-E_(3)^(@))=(-2E_(1)^(@))-(-E_(2)^(@))` or `" " E_(3)^(@)=2E_(1)^(@)-E_(2)^(@)=(2xx0.337)-(0.153)` =(0.674-0.153)=0.521 V

Discussion

1115.	An indicator electrode is :A. Glass electrodeB. `H`-electrodeC. Quinhydrone electrodeD. Calomel electrode
Answer» Correct Answer - C It is a fact.

Discussion

1116.	Which is not true for a standard hydrogen electrode ?A. The hydrogen ion concentration is 1 MB. Temperature is `25^(@)C `C. Pressure of hydrogen is 1 atmD. It contains a metallic conductor which does not adsorb hydrogen
Answer» Correct Answer - D The metal should be capable of absorbing H (e.g., Pt) .

Discussion

1117.	Indicator electrode isA. SHEB. Calomel electrodeC. `Sn^(4+) \|Sn^(2+)` electrodeD. `Zn\|ZnSO_(4)` electrode
Answer» Correct Answer - C The electrode which potential depend on Conc.of solution is called indicator electrode .

Discussion

1118.	A half-cell reaction is one thatA. takes place at one electrodeB. consumes half a unit of electricityC. goes only half way to completionD. involves only a half mole of electrolyte
Answer» Correct Answer - A A metal in contact with own ions is called as an electrode or half-cell (either oxidation or reduction reaction take place o half-cell ) . Electrochemical cell is made up of two half-cell .

Discussion

1119.	Assertion: Current stops flowing when `E_(cell)=0`. Reason: Equilibrium of the cell reaction is attained.A. Both assertion and reason are true and the reason is the correct explanation of assertion.B. Both assertion and reason are true and the reason is not the correct explanation of assertion.C. Assertion is true but the reason is false.D. Both assertion and reason are false.
Answer» Correct Answer - A

Discussion

1120.	Assertion : To obtain maximum work from a galvanic cell charge has to be passed reversibly. Reason: The reversible work done by a galvanic cell is equal to decrease in its Gibbs energy.A. If both assertion and reason are true and reason is the correct explanation of assertion .B. If both assertion and reason are true but reason is not the correct explanation of assertion .C. If assertion is true but reason is false .D. If both assertion and reason are false .
Answer» Correct Answer - A

Discussion

1121.	The calomel electrode is represented byA. `Pt , Hg_(2) Cl_(2 (s)) \|KCl _((aq)) \| Hg`B. `KCl_((aq))\| Hg_(2) Cl_(2(s)) \|Hg_((l))`C. `Hg\|KCl_((aq)) \|Hg_(2) Cl_(2(s))`D. `Hg\|HgCl_((s)) \| KCl_((aq))`
Answer» Correct Answer - B It is representation of calomel electrode .

Discussion

1122.	Assertion : Current stops flowing when `E_(cell)=0`. Reason : Equilibrium of the cell reaction is attained.A. If both assertion and reason are true and reason is the correct explanation of assertion .B. If both assertion and reason are true but reason is not the correct explanation of assertion .C. If assertion is true but reason is false .D. If both assertion and reason are false .
Answer» Correct Answer - A

Discussion

1123.	Assertion:`Cu^(2+)` ions get reduced more easily than `H^+` ions. Reason: Standard electrode potential of copper is 0.34 V.A. If both assertion and reason are true and reason is the correct explanation of assertion .B. If both assertion and reason are true but reason is not the correct explanation of assertion .C. If assertion is true but reason is false .D. If both assertion and reason are false .
Answer» Correct Answer - A

Discussion

1124.	Why is standard hydrogen electrode called reversible electrode?A. the reaction involved is standardB. it is a reference electrodeC. assigning zero electrode potential to SHE makes the calculation easyD. the potential developed by SHE is extremely small , it is arbitrarily taken as zero volt
Answer» Correct Answer - D SHE or NHE (Normal Hydrogen Electrode) is obtained by bubbling pure hydrogen gas at a net pressure of one atmosphere around platinz plate I a solution of dil. HCl having hydroge ion concentration of 1 M.

Discussion

1125.	Assertion The anode is refeeredto as an oxidation electrode while the cathode is referred to as reduction electrode. Reason When an electric current is passed through a molten electrolyte, the anions move to the anode where they lose electrons and the cations move to the cathode where they gain electrons.A. Both A and R are true and R is the correct explanation of AB. Both A and R are true but R is not a correct explanation of AC. A is true but R is falseD. Both A and R are false.
Answer» Correct Answer - A

Discussion

1126.	An electrochemical cell an behave like an electrolytic cell whenA. `E_"cell" =0`B. `E_"cell" gt E_"ext"`C. `E_"ext" gt E_"cell"`D. `E_"cell" = E_"ext"`
Answer» Correct Answer - C

Discussion

1127.	Assertion : Copper sulphate can be stored in zinc vessel. Reason : Zinc is less reactive than copper.A. Both assertion and reaction are true and the reason is correct explanation for assertionB. Both assertion and reason are true and reason is not correct explanation for assertionC. ) Assertion is true but the reason is False.D. Both assertion and reason are false.
Answer» Correct Answer - D Reason is false. Zine is more reactive than copper.

Discussion

1128.	Which of the following statement is/are not correct ?A. Zn-Cu cell is called Daniell cellB. Rust is `Fe_(2)O_(3)`C. Saline water slows down rustingD. Pure metals undergo corrosion faster than impure metals
Answer» Correct Answer - B::C::D

Discussion

1129.	The `EMF` of the cell `:` `Pt, H_(2)(1atm)\|H^(o+)(aq)\|\|AgCl\|Ag` is `0.27` and `0.26V` at `25^(@)C`, respectively. The heat of the reaction occuring inside the cell at `25^(@)C` is `………………….. kJ K^(-1)`A. `-54.8 kJ`B. `26.05 kJ`C. `-26.05 kJ`D. `+54.8 kJ`
Answer» Correct Answer - A

Discussion

1130.	Which of the following statement is/are correct ?A. One faraday is the charge carried by one mole of electronsB. If same quantity of electricity flows through the solutions of 0.1 M `AgNO_(3)` and 0.1 M `CuSO_(4)` solutions, same weight of silver and copper will be depositedC. Electrochemical equivalent has the units of grams per coulombD. Passage of one faraday of electricity produces one gram equivalent of the substance at the electode
Answer» Correct Answer - A::C::D

Discussion

1131.	Explain the following :(A) Rate of the reaction in terms of the concentration of the reactants. (B) Rate of reaction in terms of the concentration of the products.
Answer» (A) Rate of the reaction in terms of the concentration of the reactants : If c₁ and c₂ are the concentrations of the reactant A at time t₁ and t₂ respectively, then, the change in concentration, Δc = c₂ – c₁ Since c₂ < c₁, The term Δc is negative often written as – Δc. The time interval is, Δt – t₂ – t₁ If Δ [A] is the change in concentration of A, then A[A] = C₂ – C₁ ∴ Rate of the reaction = A = \(\frac{-ΔA}{Δt}\) ∴ Rate of the reaction = \(\frac{-Δc}{Δt}\) (B) Rate of the reaction in terms of the concentration of the products : If x₁ and x₂ are the concentrations of the product B at time t₁ and t₂ respectively, Then the change in concentration, Δx = x₂ – x₁. ∴ x₂ > x₁, The term Δx is positive. The time interval is, Δt = t₂ – t₁ If ΔB is the change in concentration of product B, Then, Δ[B] = x₂ – x₁ = Δx ∴ Rate of formation of B = \(+\frac{Δ[B]}{Δt}\) ∴ Rate of the reaction = \(\frac{Δx}{Δt}\)

1131.

Explain the following :(A) Rate of the reaction in terms of the concentration of the reactants. (B) Rate of reaction in terms of the concentration of the products.

Answer»

(A) Rate of the reaction in terms of the concentration of the reactants :

If c₁ and c₂ are the concentrations of the reactant A at time t₁ and t₂ respectively, then, the change in concentration,

Δc = c₂ – c₁

Since c₂ < c₁,

The term Δc is negative often written as – Δc.

The time interval is,

Δt – t₂ – t₁

If Δ [A] is the change in concentration of A,

then A[A] = C₂ – C₁

∴ Rate of the reaction = A = \(\frac{-ΔA}{Δt}\)

∴ Rate of the reaction = \(\frac{-Δc}{Δt}\)

(B) Rate of the reaction in terms of the concentration of the products :

If x₁ and x₂ are the concentrations of the product B at time t₁ and t₂ respectively,

Then the change in concentration,

Δx = x₂ – x₁.

∴ x₂ > x₁,

The term Δx is positive.

The time interval is,

Δt = t₂ – t₁

If ΔB is the change in concentration of product B,

Then,

Δ[B] = x₂ – x₁ = Δx

∴ Rate of formation of B = \(+\frac{Δ[B]}{Δt}\)

∴ Rate of the reaction = \(\frac{Δx}{Δt}\)

Discussion

1132.	The cell voltage of a galvanic cell becomes zero after using for some tme becauseA. All the free electrons are used upB. Oxidation potential of the two half cell become differentC. Reduction potential of the two half cells become equalD. Oxidation potentials of two half cells become equal in magnitude but opposite in sign.
Answer» Correct Answer - C Since `E_("red")prop[M^(n+)]` `therefore` when current is drawn the conc. Of eec trolytic solution changes and hence the reduction potential.

Discussion

1133.	The potential of hydrogen electrode having a pH=10 isA. 0.59VB. `0.59V`C. Zero votlsD. `-0.059V`
Answer» Correct Answer - B `E=0+(0.059)/(1)"log"[H^(+)]` `=0+0.059"log"10^(-10)` `0.059xx(-10)=-0.59V`.

Discussion

1134.	Zinc is used to protect corrosion of iron becauseA. `E_(oxi) ` of `ZnltE_("oxi")` of ironB. `E_("red")` of `ZnltE_("red")` of ironC. `Zn` is cheaper than ironD. Zn is abundantly available.
Answer» Correct Answer - B Zinc undergo oxidation in preference to iron.

Discussion

1135.	Li occupies higher position in the electrochemical series of metals as compared to Cu sinceA. The standard reduction potential of `Li^(+)//Li` is lowerr than that of `Cu^(2+)//Cu`B. The standard reduction potential of `Cu^(2+)//Cu` is lower than that of `Li^(+)//Li`C. The standard oxidation potential of `Li//Li^+` is lowe than that of `Cu//Cu^(2+)`D. Li is smaller in size as compared to Cu
Answer» Correct Answer - A

Discussion

1136.	Which one of the following has a potential more than zeroA. `Pt,(1)/(2)H_(2)(1atm)\|HCl(1M)`B. `Pt,(1)/(2)H_(2)(1atm)\|HCl(2M)`C. `Pt,(1)/(2)H_(2)(1atm)\|HCl(0.1M)`D. `Pt,(1)/(2)H_(2)(1atm)\|HCl(0.5M)`
Answer» Correct Answer - B

Discussion

1137.	Which of the following has highest electrode potentialA. LiB. CuC. AuD. Al
Answer» Correct Answer - C

Discussion

1138.	The standard electrode potential is measured byA. ElectrolmeterB. VoltmeterC. PyrometerD. Galvanometer
Answer» Correct Answer - B

Discussion

1139.	The strongest reducing agent of the alkali metal isA. LiB. NaC. KD. Cs
Answer» Correct Answer - A Lithium is the strongest reducing agent of te alkali metals.

Discussion

1140.	A cell is containing two H electrode The negative electrode is in contact with a solution of pH =6 eMF of the cell is 0.118 V at `25^(@)C` calculate conc of H ions ?
Answer» Correct Answer - D

Discussion

1141.	Can a solution of 1 M copper sulphate be stored in a vessel made of nickel metal? Given that `E_(Ni,Ni^(2+))^(@)=+0.25" volt ",E_(Cu,Cu^(2+))^(@)=-0.34` volt. Can nickel spatula be used to stir a solution of copper sulphate? Support your answer with a reason. `E_(Ni^(2+)//Ni)^(@)=-0.25V,E_(Cu^(2+)//Cu)^(@)=+0.34V`.
Answer» In this problem, we want to see whether the following reaction takes place or not: `Ni+CuSO_(4)toNiSO_(4)+Cu," i.e., "Ni+Cu^(2+) to Ni^(2+) +Cu` By convention, the cell may be represented as: `Ni\|Ni^(2+)\|\|Cu^(2+)\|Cu` `E_(Ni,Ni^(2+))^(@)=+0.25" volt" and E_(Cu,Cu^(2+))^(@)=-0.34" volt"` Hence, the reduction potential will be `E_(Ni^(2+),Ni)^(@)=-E_(Ni,Ni^(2+))^(@)=-0.25" volt " and E_(Cu^(2+),Cu)^(@)=-E_(Cu,Cu^(2+))^(@)=+0.34" volt"` `E_(cell)^(@)=E_(RHS" electrode")^(@)-E_("L.H.S. electrode")^(@)=+0.34-(-0.25)=+0.59` volt Thus, EMF comes out to be positive. this implies that `CuSO_(4)` reacts with nickel. hence, `CuSO_(4)` cannot be sotred in nickel vessel.

Discussion

1142.	Calculate e.m.f. of the cell containing nickel and copper electrodes. Given that : `E_(Ni^(2+)//Ni)^(@)=-0.25 V , E_(Cu^(2+)//Cu)^(@)=+0.34 V.`
Answer» `E_(cell)^(@)=E_(cathode)^(@)-E_(anode)^(@)` `=(E_(Cu^(2+)//Cu)^(@))-(E_(Ni^(2+)//Ni)^(@))=0.34-(-0.25)=0.59 V.`

Discussion

1143.	Using the standard electrode potentials given in the electrode potential series, predict if the reaction between the following is feasible`:` `a. Fe^(3+)(aq)` and `I^(-)(aq)` `b.` `Ag^(o+)(aq)` and `Cu(s)` `c.` `Fe^(3+)(aq)` and `Br^(-)(aq)` `d.` `Ag(s)` and `Fe^(3+)(aq)` `e. ``Br_(2)(aq)` and `Fe^(2+)(aq)`.
Answer» The reaction is feasible if the EMF of the cell reaction is positive (i). `Fe^(3+)(aq)+I^(-)(aq)toFe^(2+)(aq)+(1)/(2)I_(2)(g)` i.e., `Pt//I_(2)//I^(-)(aq)\|\|Fe^(3+)(aq)\|Fe^(2+)(aq)\|Pt` `E_(cell)^(@)=E_(Fe^(3+),Fe^(2+))^(@)-E_(1//2I_(1),I^(-))^(@)` `=0.77-0.54=0.23V` (Feasible) (ii). `2Ag^(+)(aq)+Cu(s)to2Ag(s)+Cu^(2+)(aq)` i.e., `Cu\|Cu^(2+)(aq)\|\|Ag^(+)(aq)\|Ag` `E_(cell)=E_(Ag^(+),Ag)-E_(Cu^(2+),Cu)^(@)` `=0.80-0.34=0.46V` (feasible) (iii). `Fe^(3+)(aq)+Br^(-)(aq)toFe^(2+)(aq)+(1)/(2)Br_(2)(g)` `E_(cell)^(@)=0.77-1.09=-0.32V` (Not feasible) (iv). `Ag(s)+Fe^(3+)(aq)toAg^(+)(aq)+Fe^(2+)(aq)` `E_(Cell)^(@)=0.77-0.80=-0.03`V (Not feasible) (v). `(1)/(2)Br_(2)(g)+Fe^(+2)(aq)toBr^(-)(aq)+Fe^(3+)(aq)` `E_(cell)^(@)=1.09-0.77=0.32V` (Feasible).

Discussion

1144.	In which of the following reactions, oxidation and reduction take place ? (i) `Zn to Zn^(2+)+2e^(-)` (ii) `Sn^(4+)+2e^(-) to Sn^(2+)`
Answer» (i) Oxidation (ii) Reduction.

Discussion

1145.	For a reaction `A(s)+2B^(+) (aq) rarr A^(2+) (aq) rarr A^(2+)(aq)+2B, K_(C)` has been found to be `10^(12)`. The `E_("cell")^(@)` is 0.354 VA. 0.354 VB. 0.708 VC. 0.0098 VD. 1.36 V
Answer» Correct Answer - A We know that `DeltaG^(@)=-2.303 RT log K_(C)` `=-2.303 RT log 10^(12)=-12xx2.303 RT` also `DeltaG^(@)=-nFE_("cell")^(@)` or `E_("cell")^(@)=(2.303 RT)/(nF)xx12=0.059/2xx12, (n=2) =0.354 V`

Discussion

1146.	The value of `E_("cell")` of hydrogen electrode at `pH=0` 298 K and 1 atm, isA. 0.59 VB. 0 VC. `-0.59 V`D. `-0.059 V`
Answer» Correct Answer - B `E_("cell")=E^(@)=pHxx0.059=0.00-(0)xx0.059` (For hydrogen electrode, `E^(@)=0`) `=0.0V`

Discussion

1147.	The equivalent conductance of solution is …… . [If cell constant is `1.25 cm^(-1)` and resistance of `N//10` solution is `2.5xx10^(3) Omega`].A. `2.5 Omega^(-1) cm^(2)" equiv"^(-1)`B. `2.5 Omega^(-1) cm^(-2)" equiv"^(-1)`C. `50 Omega^(-1) cm^(2)" equiv"^(-1)`D. `5.0 Omega^(-1) cm^(2)" equiv"^(-1)`
Answer» Correct Answer - D `k=("Cell constant")/("Resistance")=1.25/(2.5xx10^(3))=5xx10^(-4) Omega^(-1) cm^(-1)` Equivalent conductance `=(kxx1000)/(M)` `=(5xx10^(-4) xx1000)/(1//10)` `=5Omega^(-1) cm^(2)" equiv"^(-1)`

Discussion

1148.	Ammonium perchlorate, `NH_4ClO_4` , used in the solid fuel in the booster rockets on the space shuttle, is prepared from sodium perchlorate, `NaClO_4` , which is produced commercially by the electrolysis of a hot, stirred solution of sodium chloride. How many faradays are required to produce 1.0kg of sodium perchlorate? `NaCl+4H_2OtoNaClO_4+4H_2`A. 40.3B. 18.3C. 31.6D. 65.3
Answer» Correct Answer - D

Discussion

1149.	When the sample of copper with zinc impurityn is to be purified by electrolysis, the appropriate electrode are .A. Cathode=Pure zine,Anode= Pure copperB. Cathode= Impure, sample. Anode = Pure copperC. Cthode=Imure zinc, Anode= Impure sampleD. Cathode,=Pure copper, Anode= Impure sample
Answer» Correct Answer - D Impure metal will be anode while pure metal will be cathode .

Discussion

1150.	When the sample of copper with zinc impurityn is to be purified by electrolysis, the appropriate electrode are .
Answer» Correct Answer - D Impure metal made anode while pure metal made cathode.

Discussion

Explore topic-wise InterviewSolutions in .

The standard H electrode is written asA. `Pt |H_(2)| H^(+) (a = 1)`B. `Pt|H_(2)|H^(+)`C. `H^(+) (a = 1) | H_(2 (g)) |Pt`D. `H^(+) (a = 1) | H_(2 (s)) | Pt`

For the cell reaction, `underset((C_(1)))(Cu^(2+)) (aq.)+Zn(s) rarr underset((C_(2)))(Zn^(2+))(aq.)+Cu(s)` the change in free energy `(Delta G)` at a given temperature is a function of:A. `ln C_(1)`B. `ln ((C_(2))/(C_(1)))`C. `ln (C_(1)+C_(2))`D. `ln C_(2)`

Standard electrode potential of an electrode is :A. Intensive propertyB. Extensive propertyC. Isothermal propertyD. Isobaric property

A gas X at 1 atm is bubbles through a solution containing a mixture of 1M `Y^(-) and MZ^(-)` at `25^(@)C` If the reduction potential of ZgtYgtX, then,A. Y will oxidize X and not ZB. Y will oxidize Z and not XC. Y will oxidize both X and ZD. Y will reduce both X and Z

A gas X at 1 atm pressure is bubbled through a solution containing a mixture of `1 M Y^(-)` and `1 MZ^(-)` at `25^(@)C`. If the reduction potential of `Z gt Ygt X`, thenA. Y will oxidise X and not ZB. Y will oxidise Z and not XC. Y will oxidise both Z and X.D. Y will oxidise both X and Z.

A gas X at 1 atm is bubbled through a solution containing a mixture of `1 M Y^(-)` and `1 M Z^(-)` at `25^(@)C`. If the order of reduction potentials is `Z gt Y gt X`, thenA. Y will oxidise X and not ZB. Y will oxidise Z and not XC. Y will oxidise both X and ZD. Y will reduce both X and Z

The standard reduction potential values of three metallic cation `X, Y, Z` are `0.52, -3.03` and `-1.18 V` respectively. The order of reducing power to the corresponding metals is:A. `Y gt Z gt X`B. `X gt Y gt Z`C. `Z gt Y gt X`D. `Z gt X gt Y`

The standard reduction potential of three metallic cations X,Y and Z are +0.52, -0.52, 3.03 and -1.18 V respectively. The order of reducing power is :A. `Y gt Z gt X`B. `X gt Y gt Z`C. `Z gt Y gt X`D. `Z gt X gt Y`

When iron is rusted, it isA. reducedB. oxidisedC. evaporatedD. decomposed

The reduction potential of a hydrogen electrode at `pH 10` at `298K` is : `(p =1` atm)A. `0.51` voltB. 0 voltC. `-0.591` voltD. `0.059` volt

The standard reduction potential values of three metallic cation `X, Y, Z` are `0.52, -3.03` and `-1.18 V` respectively. The order of reducing power to the corresponding metals is:A. `Y gt Z gt X`B. `X gt Y gt Z`C. `Z gt Y gt X`D. `Z gt X gt Y`,

Given: (i) `Cu^(2+)+2e^(-) rarr Cu, E^(@) = 0.337 V` (ii) `Cu^(2+)+e^(-) rarr Cu^(+), E^(@) = 0.153 V` Electrode potential, `E^(@)` for the reaction, `Cu^(+)+e^(-) rarr Cu`, will beA. 0.52 VB. 0.90 VC. 0.30 VD. 0.38 V

Given: (i) `Cu^(2+)+2e^(-) rarr Cu, E^(@) = 0.337 V` (ii) `Cu^(2+)+e^(-) rarr Cu^(+), E^(@) = 0.153 V` Electrode potential, `E^(@)` for the reaction, `Cu^(+)+e^(-) rarr Cu`, will be

An indicator electrode is :A. Glass electrodeB. `H`-electrodeC. Quinhydrone electrodeD. Calomel electrode

Which is not true for a standard hydrogen electrode ?A. The hydrogen ion concentration is 1 MB. Temperature is `25^(@)C `C. Pressure of hydrogen is 1 atmD. It contains a metallic conductor which does not adsorb hydrogen

Indicator electrode isA. SHEB. Calomel electrodeC. `Sn^(4+) |Sn^(2+)` electrodeD. `Zn|ZnSO_(4)` electrode

A half-cell reaction is one thatA. takes place at one electrodeB. consumes half a unit of electricityC. goes only half way to completionD. involves only a half mole of electrolyte

The calomel electrode is represented byA. `Pt , Hg_(2) Cl_(2 (s)) |KCl _((aq)) | Hg`B. `KCl_((aq))| Hg_(2) Cl_(2(s)) |Hg_((l))`C. `Hg|KCl_((aq)) |Hg_(2) Cl_(2(s))`D. `Hg|HgCl_((s)) | KCl_((aq))`

Why is standard hydrogen electrode called reversible electrode?A. the reaction involved is standardB. it is a reference electrodeC. assigning zero electrode potential to SHE makes the calculation easyD. the potential developed by SHE is extremely small , it is arbitrarily taken as zero volt

An electrochemical cell an behave like an electrolytic cell whenA. `E_"cell" =0`B. `E_"cell" gt E_"ext"`C. `E_"ext" gt E_"cell"`D. `E_"cell" = E_"ext"`

Which of the following statement is/are not correct ?A. Zn-Cu cell is called Daniell cellB. Rust is `Fe_(2)O_(3)`C. Saline water slows down rustingD. Pure metals undergo corrosion faster than impure metals

The `EMF` of the cell `:` `Pt, H_(2)(1atm)|H^(o+)(aq)||AgCl|Ag` is `0.27` and `0.26V` at `25^(@)C`, respectively. The heat of the reaction occuring inside the cell at `25^(@)C` is `………………….. kJ K^(-1)`A. `-54.8 kJ`B. `26.05 kJ`C. `-26.05 kJ`D. `+54.8 kJ`

Explain the following :(A) Rate of the reaction in terms of the concentration of the reactants. (B) Rate of reaction in terms of the concentration of the products.

The potential of hydrogen electrode having a pH=10 isA. 0.59VB. `0.59V`C. Zero votlsD. `-0.059V`

Zinc is used to protect corrosion of iron becauseA. `E_(oxi) ` of `ZnltE_("oxi")` of ironB. `E_("red")` of `ZnltE_("red")` of ironC. `Zn` is cheaper than ironD. Zn is abundantly available.

Which one of the following has a potential more than zeroA. `Pt,(1)/(2)H_(2)(1atm)|HCl(1M)`B. `Pt,(1)/(2)H_(2)(1atm)|HCl(2M)`C. `Pt,(1)/(2)H_(2)(1atm)|HCl(0.1M)`D. `Pt,(1)/(2)H_(2)(1atm)|HCl(0.5M)`

Which of the following has highest electrode potentialA. LiB. CuC. AuD. Al

The standard electrode potential is measured byA. ElectrolmeterB. VoltmeterC. PyrometerD. Galvanometer

The strongest reducing agent of the alkali metal isA. LiB. NaC. KD. Cs

A cell is containing two H electrode The negative electrode is in contact with a solution of pH =6 eMF of the cell is 0.118 V at `25^(@)C` calculate conc of H ions ?

Calculate e.m.f. of the cell containing nickel and copper electrodes. Given that : `E_(Ni^(2+)//Ni)^(@)=-0.25 V , E_(Cu^(2+)//Cu)^(@)=+0.34 V.`

In which of the following reactions, oxidation and reduction take place ? (i) `Zn to Zn^(2+)+2e^(-)` (ii) `Sn^(4+)+2e^(-) to Sn^(2+)`

For a reaction `A(s)+2B^(+) (aq) rarr A^(2+) (aq) rarr A^(2+)(aq)+2B, K_(C)` has been found to be `10^(12)`. The `E_("cell")^(@)` is 0.354 VA. 0.354 VB. 0.708 VC. 0.0098 VD. 1.36 V

The value of `E_("cell")` of hydrogen electrode at `pH=0` 298 K and 1 atm, isA. 0.59 VB. 0 VC. `-0.59 V`D. `-0.059 V`

When the sample of copper with zinc impurityn is to be purified by electrolysis, the appropriate electrode are .A. Cathode=Pure zine,Anode= Pure copperB. Cathode= Impure, sample. Anode = Pure copperC. Cthode=Imure zinc, Anode= Impure sampleD. Cathode,=Pure copper, Anode= Impure sample

When the sample of copper with zinc impurityn is to be purified by electrolysis, the appropriate electrode are .