3195 + Interview Questions in ELECTROCHEMISTRY IN GENERAL AWARENESS Page 39 InterviewSolution

1901.	Consider the following reaction, `Cu\|Cu^(2+) (1M)\|\|(Zn^(2+)(1 M)\|Zn` A cell represented above should have emfA. positiveB. negativeC. zeroD. cannot be predicted.
Answer» Correct Answer - B `E_("red")^(@)` of copper `gtE_("red")^(@)` of Zn.

Discussion

1902.	The volume of `2M` barium premanganate required to react completely, with `5 mL` of `3 M` lead oxalate soultion in acidic medium is :A. `1 mL`B. `2 mL`C. `3 mL`D. `6 mL`
Answer» Correct Answer - C Meq. of `Ba(MnO_(4))_(2) =` Meq. Of lead oxalate `2 xx 5 xx V = 5 xx 3 xx 2` `V = 3mL` (v.f. for `Ba(MnO_(4))_(2)` and oxlate are `5` and `2` respectively

Discussion

1903.	Four Faraday of electricity were passed through aqueous solutions of `AgNO_(3), NiSO_(4), FeCl_(3)` and `PbCl_(4)` kept in four vessels using inert electrodes. The ratio moles of `Ag, Ni, Fe` and `Pb` depositeed will be :A. `12 : 6 : 4 : 3`B. `12 : 4 : 6 : 3`C. `4 : 3 : 2 : 1`D. `1 : 2 : 3 : 4`
Answer» Correct Answer - A `{:("species","faradays","No. of moles"),(,"passed","deposited"),(AgNO_(3)(Ag^(+)),4,4),(NiSO_(4)(Ni^(2+)),4,4//2),(FeCl_(3)(Fe^(3+)),4,4//3),(PbCl_(4)(Pb^(4+)),4,4//4):}`

Discussion

1904.	The molar conductivities `Lambda_(NaOAc)^@` and `Lambda_(HCI)^@` at infinite dilution is watter at `25^@C` are `91.0` and `426.2 S cm^@ //`mol respectively. To calculate `Lambda_(HOAc,)^2` the additional value required is:A. `Lambda_(H_(2)O)^(@)`B. `Lambda_(KCl)^(@)`C. `Lambda_(NaOH)^(@)`D. `Lambda_(NaCl)^(@)`
Answer» Correct Answer - D According to Kohlrausch law : `Lambda_(HOAc)^(@) = Lambda_(NaOAC)^(@) + Lambda_(HCl)^(@) - Lambda_(NaCl)^(@)`

Discussion

1905.	In the reaction : `XCrCl_(3) + YH_(2)O_(2) rarr ZNaOH rarr Na_(2)CrO_(4) + NaCl + H_(2)O` The values of `X, Y` and `Z` are respectively :A. `2, 6, 5`B. `2, 5, 6`C. `2, 3, 10`D. `2, 3, 8`
Answer» Correct Answer - C Balance the equation.

Discussion

1906.	The standard reduction potential for half reactions for four different elements. `A, B, C` and `D` are: (i) `A_(2) + 2e^(-) rarr 2A^(-), E^(@) = + 2.85 V` (ii) `B_(2) + 2e^(-) rarr 2B^(-), E^(@) = + 1.36 V` (iii) `C_(2) + 2e^(-) rarr 2C^(-), E^(@) = + 1.06 V` (iv) `D_(2) + 2e^(-) rarr 2D^(-), E^(@) = + 0.53 V` The strongest oxidising reducing agents smong these :A. Would be `A` and `D` respectivelyB. Would be `D` and `A` respectivelyC. Would be `B` and `C` respectivelyD. Cannot be ascertained from the given data as the species being subjected to ioxidation or reduction have not been indicated
Answer» Correct Answer - A Strongest oxidising agent has higher reduction potential. Strongest reducing agent has lowest reduction potential.

Discussion

1907.	The correct order of mobility of alkali metal ions in aqueous solution isA. ` K^+ gt Rb^+ gt Na^+ gt Li^+`B. ` Rb^+ gt K^+ gt Na^+ gt Li^+`C. `Li^+ gt Na^+ gt K^+ gt Rb^+`D. ` Na^+ gt K^+ gt Rb^+ gt Li^+`
Answer» Correct Answer - B Smaller is the size of ion , more is hydration, lesser is mobilitey, i.e , mobitlity of ion in aqueous solution decreses whith decrease in size of hyerated ion. S

Discussion

1908.	Efficiency of a cell reaction under standard conditions, `A_((s)) + B^(+) rarr A^(+) + B_(s), DeltaH^(@) = -300 kJ` is `70%`. The standard electrode potential of cell is :A. `2.176 V`B. `+ 2 .876 V`C. `1.248 V`D. `+ 1.648 V`
Answer» Correct Answer - A Efficiency `= (DeltaG^(@))/(DeltaH^(@)) = (nE^(@)F)/(DeltaH^(@))` `E^(@) = ("Efficiency" xx DeltaH^(@))/(-nF)` `= (70 xx (-300 xx 10^(+3)))/(1000 xx (-1) xx 96500) = 2.176 V`

Discussion

1909.	The ionic mobility of alkali metal ions in aqueous solution is maximum for:A. `K^(+)`B. `Rb^(+)`C. `Li^(+)`D. `Na^(+)`
Answer» Correct Answer - B The hydrateed ion size is : `Li_((aq.))^(+) gt Na_((aq.))^(+) gt K_((aq.))^(+) gt Rb_((aq.))^(+)` Larger is size of ion, lesser is its conductance.

Discussion

1910.	If `e_(Fe^(2+) //Fe)^@ =- 0. 44 1V`. And `E_(Fe^(3+)//Fe^(2+))^(o) = 0. 771 V`. The standard emf of the reaction ` Fe +2 Fe^(3+) rarr 3Fe^(2+)` will be .A. `1.212 V`B. `0.111 V`C. `0.330 V`D. `1.653 V`
Answer» Correct Answer - A `E_("cell") = E_(Fe//Fe^(2+))^(@) + E_(Fe^(3+)//Fe^(2+))^(@)` `= 0.441 + 0.771 = 1.212 V`

Discussion

1911.	The correct order of mobility of alkali metal ions in aqueous solution isA. `K^(+) gt Rb^(+) gt Na^(+) gt Li^(+)`B. `Rb^(+) gt K^(+) gt Na^(+) gt Li^(+)`C. `Li^(+) gt Na^(+) gt K^(+) gt Rb^(+)`D. `Na^(+) gt K^(+) gt Rb^(+) gt Li^(+)`
Answer» Correct Answer - B Smaller is size of hydrated ion, more is ionic mobility size : `Li_((aq.))^(+) lt Na_((aq.))^(+) lt K_((aq.))^(+) lt Rb_((aq.))^(+)`

Discussion

1912.	Charge required to liberated `11.5 g` sodium is .A. 0.5FB. 0.1FC. 1.5FD. 96500 colombs
Answer» Correct Answer - A `Na^(+)+e^(-)toNa` Charge (in F)=moles of `e^(-)` used=moles of Na deposited `=(11.5)/(23)gm=0.5` faraday.

Discussion

1913.	Chemically, rust is _______
Answer» Hydrated ferric oxide (Fe₂O₃.xH₂O)

Discussion

1914.	A hyptherical electrochemical cell is given as `A^(Ө)\|A^+ (xM) \|\| B^+ (yM) \| B^(Ө)` The emf masured is `+ 0. 20 V`. The cell reaction is .A. `A + B^(+) rarr A^(+) + B`B. `A^(+) + B rarr A + B^(+)`C. `A^(+) + e rarr A, + B^(+) + e rarr B`D. cannot be predicted
Answer» Correct Answer - A `E_("cell") = +ve`, then `{:(ArarrA^(+)+e),(B^(+)+erarrB):}/(A+B^(+)rarrA^(+)+B)`

Discussion

1915.	Which of the following is not correct for a fuel cell?A. It can strore chemical energyB. Reactants are continously spplied to the cellC. Products are continuosly removed from the cellD. It is a voltaic cell
Answer» Correct Answer - A A fuel cell is essentially a battery but if differs by operating with a continuous supply of energetic reactants, or fuel. The first fuel cell was invented in `1839` by William Groves. He obtained the cell b y electrolyzing water and collecting the `H_(2)` and `O_(2)` in small, inverted test tubes. After removing the battery current would flow from the cell. In effect, the electrolysis charged the cell, after which it operated as a fuel cell. In its simplest form, `H_(2)//O_(2)` fuel cell consists of an electrolyte solution, such as sodium or potassium hydroxide solution, and two inert electrodes. `H_(2)` and `O_(2)` gases are bubbled through the anode and cathode compartments. Unlike batteries, fuel cell do not store chemical energy.

Discussion

1916.	The free energy change in related to equilibrium constant asA. `DeltaG=RT` in `k_(c)`B. `-DeltaG=RT "log" k_(c)`C. `-DeltaG=2.303 Rt "log" k_(c)`D. `-DeltaG=(RT"log"k_(c))//2.303`.
Answer» Correct Answer - C `-DeltaG=2.303 Rt` log `k_(c)`

Discussion

1917.	A hyptherical electrochemical cell is given as `A^(Ө)\|A^+ (xM) \|\| B^+ (yM) \| B^(Ө)` The emf masured is `+ 0. 20 V`. The cell reaction is .A. The cell raction cannot be prdictedB. `1 A+B^+ rarr A^+ + B`C. ` A^+ +B rarr A+B^+`D. ` A^+ +e^- rarr A, V^+ e^(-) rarr B`
Answer» Correct Answer - B `E_("cell") = + ve ` thus redox changes are `A rarr A^+ =e^- LHS ` shows reductio . `B^+ +e rarr` B RHS shows reduction `A+B^+ rarr A^+ +B` .

Discussion

1918.	Electrolysis involves oxidation and reduction respectively at .A. Anode and cathodeB. Cathode and anodeC. At both the electrodesD. none of the above
Answer» Correct Answer - A In electrolysis process oxidation occurs at anode and reduction occurs at cathode.

Discussion

1919.	Chemically rust isA. `Fe(OH)_(3)`B. `Fe(OH)_(2)`C. `Fe_(2)O_(3)`D. `Fe_(2)O_(3).xH_(2)O`
Answer» Correct Answer - D Rust is an hydrated oxide of iron, mainly `Fe_(2)O_(3).xH_(2)O` formed on the surface of iron when it is exposed to moisture and air. Consider the rusting that occurs when a drop of water is in contact with iron. The edge of the water drop exposed to the air becomes one pole of a voltaic cell. At this edge, molecular `O_(2)` from air is reduced to hydroxide ion in solution. `O_(2)(g)+2H_(2)O(l)+4e^(-) rarr 4OH^(-)(aq.)` The electrons for this reduciton are supplied by the oxidation of metallic iron to the edge of the drop. Thus, the metallic iron funcations, as the ecternal circuit between the cell poles. Ions move within the water drop, completing the electric circuit, Iron `(II)` iron move outward from tghe center of the drop, and hydroxide ions move inward from the edge. The two ions meet in a doughnut-shaped region, where they react to precipitate iron `(II)` hydroxide. `Fe^(2+)(aq.)+2OH^(-)(aq.) rarr Fe(OH)_(2)(s)` This precipitate is quickly oxidized by `O_(2)` to rust (approxi-mated by the formula `Fe_(2)O_(3).H_(2)O)`. `4Fe^(OH)_(2)(s)+O_(2)(g) rarr 2Fe_(2)O_(3).H_(2)O(s)+2H_(2)O(l)` Thus rust is formed between the anode and cathode. We can regard rust as a mixture of `Fe_(2)O_(3)` and `Fe(OH)_(3)`.

Discussion

1920.	Corrosion ofA. an oxidation processB. a redox processC. a redox processD. neither an oxidation nor a redox process
Answer» Correct Answer - C Corrosion processes are electron trsfers, oxidation-reduction processes that occur when the surface of a metal is in contact with atmosphere. A potential difference in the composition of the metal, which aries from lattice defects, imprities, or even partial oxidation. This potential difference makes it possible for a corrosion process resembling the operation of a galvanic cell to take place on the metal surface. The site of oxidation and the site of the reduction can be separeted in space. Electrons flow betwenn these sites through electrical connection of a glavanic cell. Water vapor that condness on the metal surface provides the solution through which the ions flow.

Discussion

1921.	The relationship between free energy and electrode potential isA. `DeltaG=nEF`B. `DeltaG=nFE`C. `DeltaG=(nFE)/(R)`D. `DeltaG=(DeltaH)/(nFE)`
Answer» Correct Answer - A `DeltaG=-nFe` +2

Discussion

1922.	Which of the following involves the reduction of copper:A. `Cu(s)+(1)/(2)O_(2)(g)rarrCuO(s)`B. `Cu^(2+)(aq)+2I^(-)(aq)rarr2Cul(aq)`C. `CuCl_(2)(g)+2F^(-)(aq)rarrCuF_(2)+Cl_(2)(g)`D. None of the above.
Answer» Correct Answer - B `Cu^(+)rarrCu^(1)` decrease in O.N. Reduction

Discussion

1923.	In which of the following will the corrosion of iron be most rapid?A. In air and saline waterB. In air and moistureC. In pure oxygenD. In pure water
Answer» Correct Answer - A Oxygen gas and water must be present for iron to rust. Corrosion usually occurs faster near the sea, because droplets of water in the air contain dissolved salts such as sodlim chloride, forming an ionic solution that conducts electricity better than pure water does.

Discussion

1924.	Which one of the following metal can decompose copper sulphate solution?A. MercuryB. IronC. GoldD. Platinum.
Answer» Correct Answer - B Because iron has lesser reduction potential and is more active than copper.,

Discussion

1925.	In which of the following, the corrosion of iron will be most rapid?A. In pure waterB. In pure oxygenC. In air and moistureD. In air and saline water
Answer» Correct Answer - D Corrosion is speed up by air, water, electrolytes and impurities in metal.

Discussion

1926.	Given below are half-cell reaction: `Mn^(2+)+2e^(-) rarr Mn,, E^(@) = -1.81 V` `2(Mn^(3+)+e^(-) rarr Mn^(2+)),, E^(@) = +1.51 V` The `E^(@)` for `3Mn^(2+) rarr Mn+2Mn^(3+)` will be:A. `-2.69V`, the reaction will not occurB. `-2.69V`, the reaction will occurC. `-0.33V`, the reaction will not occurD. `-0.33V`, the reaction will occur
Answer» Correct Answer - a

Discussion

1927.	The chemical reaction: `Zn^(2+)+2e^(-)rarrZn` Is an example ofA. Redox processB. Reversible processC. OxidationD. Reduction
Answer» Correct Answer - D It is oxidation `becauseO.N`. Increases.

Discussion

1928.	In which of the following, the corrosion of iron will be most rapid?A. In pure waterB. In pure oxygenC. In air and moistureD. In air and saline water.
Answer» Correct Answer - D Corrosion is rapid in electrolysis.

Discussion

1929.	Conductivity of a solution is directly proportional toA. DilutionB. Number of ionsC. Current densityD. Volume of the solution
Answer» Correct Answer - B Conductivity of a solution is directly proportional to the number of ions.

Discussion

1930.	When a solution of an electrolyte is heated the conductance of the solutionA. Increases because of the electrolyte conducts betterB. Decreases because of the increased heatC. Decreases because of the dissociation of the electrolyte is suppressedD. Increases because the electrolyte is dissociated more
Answer» Correct Answer - D Degree of dissociation of weak electrolyte increases on increasing temperature.

Discussion

1931.	In electrochemical corrosion of metals, the metal undergoing corrosionA. becomes anodeB. becomes cathodeC. becomes inertD. none is correct.
Answer» Correct Answer - A Pure metal acts as anode where as impurities as cathode.

Discussion

1932.	For spontaneity of a cell, which is correct?A. `DeltaG= 0.DeltaE=0`B. `DeltaG=-ve,DeltaE=0`C. `DeltaG=+ve,DeltaE=0`D. `DeltaG=-ve`
Answer» Correct Answer - D For spontaneity of a cell `DeltaGlt0`

Discussion

1933.	The hydrogen electrdoe is dipped in a solution of pH=3 at `25^(@)C` the potential of the cell would be (the value of 2.303 RT/F is 0.059 V)A. 0.177VB. 0.087VC. `-0.177V`D. `0.059V`
Answer» Correct Answer - C `pH=3` `therefore [H^(+)]=10^(-3)` `H^(+)+e^(-)rarr(1)/(2)H_(2)` `E=E^(@)-(0.059)/(n)"log" (1)/([H^(+)])=0-(0.059)/(1)"log"10^(3)` ` E=-0.177V`

Discussion

1934.	How much charge s requireed to produce `H_(2)` fas at the rate of `1 mL sec^(-1)` by the electrolysis of molten `NaCl` ?A. `8.6 C`B. `18.4 C`C. `4.3 C`D. `1.4 C`
Answer» Correct Answer - A `1` eq. or `11.2` litre `H_(2) = 96500C` `:. 1 mL H_(2) = (96500)/(11200) = 8.6C`

Discussion

1935.	`K_(d)` for dissociation of `[Ag(NH_(3))_(2)]^(+)` into `Ag^(+)` and `NH_(3)` is `6 xx 10^(-8)`. Calculae `E^(@)` for the following half reaction. `AG(NH_(3))_(2)^(+) +e^(-) rarr Ag +2NH_(3)` Given `Ag^(+) +e^(-) rarr Ag, E^(@) = 7.99V`
Answer» Correct Answer - `0.373V` `Ag rarr Ag^(+) +e^(-) E_(RP) = 0.799V` `Ag(NH_(3))_(2)^(+) +e rarr Ag +2 NH_(3) E_(RP) = ?` `Ag(NH_(3))_(2)^(+) hArr Ag^(+) +2 NH_(3)` `E_(cell) = E_(cell)^(@) +(0.0591)/(1)log_(10).([Ag(NH_(3))_(2)^(+)])/([Ag^(+)][NH_(3)]^(2))` `0 =E_(cell)^(@) +(0.0591)/(1)log(6 xx 10^(-8)) rArr E_(cell)^(@) =- 0.426` `E_(cell)^(@) = E_(C)^(@) - E_(A)^(@)` `-0.426 =E_(C)^(@) - 0.799 rArr E_(C)^(@) = 0.373 V`

Discussion

1936.	When 0.04 faraday of electrcity is passed through a solution of `CaSO_4`. Then the weight of `Ca^(2+)` metal deposited at the cathode isA. 0.2 gmB. 0.4 gmC. 0.6 gmD. 0.8 gm
Answer» Correct Answer - D `Ca^(++)+2e^(-)toCa` `E_(Ca)=(40)/(2)=20` `W_(Ca)=E_(Ca)xx`No.of faradays=`20xx0.04=0.8gm`

Discussion

1937.	Column-1 and column-II contains four entries each. Entries of column-I are to be matched with some entries of column-II .One or more than one entries of column-I may have the matching with the same entries of column-II
Answer» Correct Answer - A::B::C::D

Discussion

1938.	Column-1 and column-II contains four entries each. Entries of column-I are to be matched with some entries of column-II .One or more than one entries of column-I may have the matching with the same entries of column-II
Answer» Correct Answer - A::B::C::D

Discussion

1939.	Column-1 and column-II contains four entries each. Entries of column-I are to be matched with some entries of column-II .One or more than one entries of column-I may have the matching with the same entries of column-II
Answer» Correct Answer - A::B::C::D

Discussion

1940.	If the pressure of ` H_2` gas is increase from (1) atm to `100` atm. Keeping `H^+` concentration constatn at ` 1` M, the veltage of hydrogen half cell at `25^@ C` will be .A. 0.059VB. 0.59 VC. 0.0295 VD. 0.118V
Answer» Correct Answer - D

Discussion

1941.	A conductivity cell has been calibrited with 0.01 M electrolyte solution (`k=1.25xx10^(-3)" S "cm^(-1)`) in the cell and the measured resistance is 800 ohms at `25^(@)C`. The cell constant will be :A. `1.02 cm^(-1)`B. `0.102 cm^(-1)`C. `1.00 cm^(-1)`D. `0.5 cm^(-1)`
Answer» Correct Answer - C (c ) Specific conductance (k) `=(1)/(R )xx(1)/(a)` `(l)/(a)=kxxR` `=(1.25xx10^(-3)" ohm"^(-1)cm^(-1))xx(800" ohm")` `=1.0 cm^(-1)`

Discussion

1942.	After sometime, the voltage of an electrochemical cell becomes zero. Comment on the statement.
Answer» The statement is correct because the reduction potentials `(E^(@))` of the two electrodes become equal at that stage.

Discussion

1943.	Define specific conductivity.
Answer» It is defined as the conductance of electrolyte when distance between electrodes is 1cm. and area of cross section is 1cm².

Discussion

1944.	Why does the conductivity of a solution decrease with dilution?
Answer» Because the number of ions per unit volume decreases.

Discussion

1945.	Calculate equilibrium constant for the reaction at `25^(@)C` `Cu(s)+2Ag^(+)(aq) hArr Cu^(2+)(aq)+2Ag(s)` `E^(@)` value of the cell is 0.46`" V "`.
Answer» Correct Answer - `3.67xx10^(15)` `logK_(C)=nE_(cell)^(@)//0.0591,E_(cell)^(@)=0.46" V ",n=2` `:." "logK_(C)=(2xx0.46)/(0.0591)=15.567,k_(C)=3.67xx10^(15)`.

Discussion

1946.	Calculate the value of equilibrium constant for the reaction : `2Fe^(3+)+2I^(-) to 2Fe^(2+)+I_(2)` Given that `E_(cell)^(@)=0.235" V "`
Answer» Correct Answer - `8.97xx10^(7)` `logK_(C)=(nE_(cell)^(@))/(0.0591)=(2xx0.235)/(0.0591)=7.953,K_(C)="Antilog "7.953=8.97xx10^(7)`.

Discussion

1947.	Which solution will show greater conductance of electricity, 1 M NaCl at 293 K or 1M NaCl at 323 K and Why?
Answer» 1 M NaCl at 323 K as the ionic mobilities increase with increase in temperature.

Discussion

1948.	Calculate emf of the following cell reaction at 2968 K : `Ni(s)//Ni^(2+)(0.01 M) \|\| Cu^(2+)(0.1 M)//Cu(s)` [Given `E_(Ni^(2+)//Ni)^(@)=-0.25" V ",E_(Cu^(2+)//Cu)^(@)=+0.34 " V "`] Write the overall cell reaction.
Answer» Correct Answer - 0.6195V According toNernst Equation : `E=E^(@)-(0.0591)/(n)"log"([Ni^(2+)])/([Cu^(2+)])=0.59-(0.0591)/(2)"log"([0.01])/([0.1])` `E=0.59-0.0295(-1)=0.6195" V "`

Discussion

1949.	Which of the following pairs will have greater conduction and why?(E)(a) Copper wire at 25˚C and Copper wire at 50˚C. (b) 0.1 M acetic acid solution or 1 M acetic acid solution?
Answer» (a) Copper wire at 25˚C because with increase in temperature, resistance increase, metallic conduction decrease with increase in temp .due to vibration of kernels. (b) 0.1 M acetic acid solution because with dilution degree of dissociation increases and hence number of ions.

1949.

Which of the following pairs will have greater conduction and why?(E)(a) Copper wire at 25˚C and Copper wire at 50˚C. (b) 0.1 M acetic acid solution or 1 M acetic acid solution?

Answer»

(a) Copper wire at 25˚C because with increase in temperature, resistance increase, metallic conduction decrease with increase in temp .due to vibration of kernels.

(b) 0.1 M acetic acid solution because with dilution degree of dissociation increases and hence number of ions.

Discussion

1950.	Which of the following curve gives the variation of `Delta_(m)^(oo)` with `sqrt(C)` to `CH_(3)COOH`?A. B. C. D. None of these
Answer» Correct Answer - D See variation of `^^m` of weak electrolyte with dilution in comprehensive review.

Discussion

Explore topic-wise InterviewSolutions in .

Consider the following reaction, `Cu|Cu^(2+) (1M)||(Zn^(2+)(1 M)|Zn` A cell represented above should have emfA. positiveB. negativeC. zeroD. cannot be predicted.

The volume of `2M` barium premanganate required to react completely, with `5 mL` of `3 M` lead oxalate soultion in acidic medium is :A. `1 mL`B. `2 mL`C. `3 mL`D. `6 mL`

Four Faraday of electricity were passed through aqueous solutions of `AgNO_(3), NiSO_(4), FeCl_(3)` and `PbCl_(4)` kept in four vessels using inert electrodes. The ratio moles of `Ag, Ni, Fe` and `Pb` depositeed will be :A. `12 : 6 : 4 : 3`B. `12 : 4 : 6 : 3`C. `4 : 3 : 2 : 1`D. `1 : 2 : 3 : 4`

In the reaction : `XCrCl_(3) + YH_(2)O_(2) rarr ZNaOH rarr Na_(2)CrO_(4) + NaCl + H_(2)O` The values of `X, Y` and `Z` are respectively :A. `2, 6, 5`B. `2, 5, 6`C. `2, 3, 10`D. `2, 3, 8`

The correct order of mobility of alkali metal ions in aqueous solution isA. ` K^+ gt Rb^+ gt Na^+ gt Li^+`B. ` Rb^+ gt K^+ gt Na^+ gt Li^+`C. `Li^+ gt Na^+ gt K^+ gt Rb^+`D. ` Na^+ gt K^+ gt Rb^+ gt Li^+`

Efficiency of a cell reaction under standard conditions, `A_((s)) + B^(+) rarr A^(+) + B_(s), DeltaH^(@) = -300 kJ` is `70%`. The standard electrode potential of cell is :A. `2.176 V`B. `+ 2 .876 V`C. `1.248 V`D. `+ 1.648 V`

The ionic mobility of alkali metal ions in aqueous solution is maximum for:A. `K^(+)`B. `Rb^(+)`C. `Li^(+)`D. `Na^(+)`

If `e_(Fe^(2+) //Fe)^@ =- 0. 44 1V`. And `E_(Fe^(3+)//Fe^(2+))^(o) = 0. 771 V`. The standard emf of the reaction ` Fe +2 Fe^(3+) rarr 3Fe^(2+)` will be .A. `1.212 V`B. `0.111 V`C. `0.330 V`D. `1.653 V`

The correct order of mobility of alkali metal ions in aqueous solution isA. `K^(+) gt Rb^(+) gt Na^(+) gt Li^(+)`B. `Rb^(+) gt K^(+) gt Na^(+) gt Li^(+)`C. `Li^(+) gt Na^(+) gt K^(+) gt Rb^(+)`D. `Na^(+) gt K^(+) gt Rb^(+) gt Li^(+)`

Charge required to liberated `11.5 g` sodium is .A. 0.5FB. 0.1FC. 1.5FD. 96500 colombs

Chemically, rust is _______

A hyptherical electrochemical cell is given as `A^(Ө)|A^+ (xM) || B^+ (yM) | B^(Ө)` The emf masured is `+ 0. 20 V`. The cell reaction is .A. `A + B^(+) rarr A^(+) + B`B. `A^(+) + B rarr A + B^(+)`C. `A^(+) + e rarr A, + B^(+) + e rarr B`D. cannot be predicted

Which of the following is not correct for a fuel cell?A. It can strore chemical energyB. Reactants are continously spplied to the cellC. Products are continuosly removed from the cellD. It is a voltaic cell

The free energy change in related to equilibrium constant asA. `DeltaG=RT` in `k_(c)`B. `-DeltaG=RT "log" k_(c)`C. `-DeltaG=2.303 Rt "log" k_(c)`D. `-DeltaG=(RT"log"k_(c))//2.303`.

A hyptherical electrochemical cell is given as `A^(Ө)|A^+ (xM) || B^+ (yM) | B^(Ө)` The emf masured is `+ 0. 20 V`. The cell reaction is .A. The cell raction cannot be prdictedB. `1 A+B^+ rarr A^+ + B`C. ` A^+ +B rarr A+B^+`D. ` A^+ +e^- rarr A, V^+ e^(-) rarr B`

Electrolysis involves oxidation and reduction respectively at .A. Anode and cathodeB. Cathode and anodeC. At both the electrodesD. none of the above

Chemically rust isA. `Fe(OH)_(3)`B. `Fe(OH)_(2)`C. `Fe_(2)O_(3)`D. `Fe_(2)O_(3).xH_(2)O`

Corrosion ofA. an oxidation processB. a redox processC. a redox processD. neither an oxidation nor a redox process

The relationship between free energy and electrode potential isA. `DeltaG=nEF`B. `DeltaG=nFE`C. `DeltaG=(nFE)/(R)`D. `DeltaG=(DeltaH)/(nFE)`

Which of the following involves the reduction of copper:A. `Cu(s)+(1)/(2)O_(2)(g)rarrCuO(s)`B. `Cu^(2+)(aq)+2I^(-)(aq)rarr2Cul(aq)`C. `CuCl_(2)(g)+2F^(-)(aq)rarrCuF_(2)+Cl_(2)(g)`D. None of the above.

In which of the following will the corrosion of iron be most rapid?A. In air and saline waterB. In air and moistureC. In pure oxygenD. In pure water

Which one of the following metal can decompose copper sulphate solution?A. MercuryB. IronC. GoldD. Platinum.

In which of the following, the corrosion of iron will be most rapid?A. In pure waterB. In pure oxygenC. In air and moistureD. In air and saline water

The chemical reaction: `Zn^(2+)+2e^(-)rarrZn` Is an example ofA. Redox processB. Reversible processC. OxidationD. Reduction

In which of the following, the corrosion of iron will be most rapid?A. In pure waterB. In pure oxygenC. In air and moistureD. In air and saline water.

Conductivity of a solution is directly proportional toA. DilutionB. Number of ionsC. Current densityD. Volume of the solution

In electrochemical corrosion of metals, the metal undergoing corrosionA. becomes anodeB. becomes cathodeC. becomes inertD. none is correct.

For spontaneity of a cell, which is correct?A. `DeltaG= 0.DeltaE=0`B. `DeltaG=-ve,DeltaE=0`C. `DeltaG=+ve,DeltaE=0`D. `DeltaG=-ve`

The hydrogen electrdoe is dipped in a solution of pH=3 at `25^(@)C` the potential of the cell would be (the value of 2.303 RT/F is 0.059 V)A. 0.177VB. 0.087VC. `-0.177V`D. `0.059V`

How much charge s requireed to produce `H_(2)` fas at the rate of `1 mL sec^(-1)` by the electrolysis of molten `NaCl` ?A. `8.6 C`B. `18.4 C`C. `4.3 C`D. `1.4 C`

`K_(d)` for dissociation of `[Ag(NH_(3))_(2)]^(+)` into `Ag^(+)` and `NH_(3)` is `6 xx 10^(-8)`. Calculae `E^(@)` for the following half reaction. `AG(NH_(3))_(2)^(+) +e^(-) rarr Ag +2NH_(3)` Given `Ag^(+) +e^(-) rarr Ag, E^(@) = 7.99V`

When 0.04 faraday of electrcity is passed through a solution of `CaSO_4`. Then the weight of `Ca^(2+)` metal deposited at the cathode isA. 0.2 gmB. 0.4 gmC. 0.6 gmD. 0.8 gm

Column-1 and column-II contains four entries each. Entries of column-I are to be matched with some entries of column-II .One or more than one entries of column-I may have the matching with the same entries of column-II

Column-1 and column-II contains four entries each. Entries of column-I are to be matched with some entries of column-II .One or more than one entries of column-I may have the matching with the same entries of column-II

Column-1 and column-II contains four entries each. Entries of column-I are to be matched with some entries of column-II .One or more than one entries of column-I may have the matching with the same entries of column-II

If the pressure of ` H_2` gas is increase from (1) atm to `100` atm. Keeping `H^+` concentration constatn at ` 1` M, the veltage of hydrogen half cell at `25^@ C` will be .A. 0.059VB. 0.59 VC. 0.0295 VD. 0.118V

A conductivity cell has been calibrited with 0.01 M electrolyte solution (`k=1.25xx10^(-3)" S "cm^(-1)`) in the cell and the measured resistance is 800 ohms at `25^(@)C`. The cell constant will be :A. `1.02 cm^(-1)`B. `0.102 cm^(-1)`C. `1.00 cm^(-1)`D. `0.5 cm^(-1)`

After sometime, the voltage of an electrochemical cell becomes zero. Comment on the statement.

Define specific conductivity.

Why does the conductivity of a solution decrease with dilution?

Calculate equilibrium constant for the reaction at `25^(@)C` `Cu(s)+2Ag^(+)(aq) hArr Cu^(2+)(aq)+2Ag(s)` `E^(@)` value of the cell is 0.46`" V "`.

Calculate the value of equilibrium constant for the reaction : `2Fe^(3+)+2I^(-) to 2Fe^(2+)+I_(2)` Given that `E_(cell)^(@)=0.235" V "`

Which solution will show greater conductance of electricity, 1 M NaCl at 293 K or 1M NaCl at 323 K and Why?

Calculate emf of the following cell reaction at 2968 K : `Ni(s)//Ni^(2+)(0.01 M) || Cu^(2+)(0.1 M)//Cu(s)` [Given `E_(Ni^(2+)//Ni)^(@)=-0.25" V ",E_(Cu^(2+)//Cu)^(@)=+0.34 " V "`] Write the overall cell reaction.

Which of the following pairs will have greater conduction and why?(E)(a) Copper wire at 25˚C and Copper wire at 50˚C. (b) 0.1 M acetic acid solution or 1 M acetic acid solution?

Which of the following curve gives the variation of `Delta_(m)^(oo)` with `sqrt(C)` to `CH_(3)COOH`?A. B. C. D. None of these