NEET > Electrochemistry

Explore popular questions from Electrochemistry for NEET. This collection covers Electrochemistry previous year NEET questions hand picked by popular teachers.


Q 1.    

Correct4

Incorrect-1

In the electrochemical cell:
{tex}\mathrm {Zn|ZnSO_4(0.01M)||CuSO_4(1.0\ M)|Cu}{/tex}, the emf of this Daniell cell is {tex}E_1{/tex}. When the concentration of {tex}\mathrm {ZnSO_4}{/tex}, is changed to {tex}\mathrm {1.0\ M}{/tex} and that of {tex}\mathrm{CuSO_4}{/tex} changed to {tex}\mathrm {0.01 M}{/tex}, the emf changes to {tex}E_2{/tex}. From the followings, which one is the relationship between {tex}E_1 {/tex}and {tex}E_2{/tex}? (Given, {tex}RT/F{/tex} = 0.059)

A

{tex} E _ { 1 } < E {/tex}

{tex} E _ { 1 } > E _ { 2 } {/tex}

C

{tex} E _ { 2 } = 0 ^ { \mathrm { 1 } } E _ { 1 } {/tex}

D

{tex} E _ { 1} ^ { \cdot } = E _ { 2 } {/tex}

Explanation


Q 2.    

Correct4

Incorrect-1

The molar conductivity of a {tex}0.5\ \mathrm { mol } / \mathrm { dm } ^ { 3 } {/tex} solution of {tex} \mathrm { AgNO } _ { 3 } {/tex} with electrolytic conductivity of {tex} 5.76 \times 10 ^ { - 3 }\ \mathrm { S } \ \mathrm { cm } ^ { - 1 } {/tex} at {tex}298\, \mathrm { K } {/tex} is

A

{tex}2.88\, \mathrm { S } \,\mathrm { cm } ^ { 2 } / \mathrm { mol } {/tex}

{tex}11.52\, \mathrm {S\,{cm } ^ { 2 }} / \mathrm { mol } {/tex}

C

{tex} 0.086\,\mathrm { S }\, \mathrm { cm } ^ { 2 } / \mathrm { mol } {/tex}

D

{tex}28.8\ \mathrm { S }\ \mathrm { cm } ^ { 2 } / \mathrm { mol } {/tex}

Explanation


Q 3.    

Correct4

Incorrect-1

During the electrolysis of molten sodium chloride, the time required to produce 0.10 mol of chlorine gas using a current of 3 amperes is

A

55 minutes

110 minutes

C

220 minutes

D

330 minutes

Explanation




Q 4.    

Correct4

Incorrect-1

If the {tex} E ^ { \circ }_{cell} {/tex} for a given reaction has a negative value, which of the following gives the correct relationships for the values of {tex} \Delta G ^ { \circ } {/tex} and {tex} K _ { \operatorname { eq } } ? {/tex}

{tex} \Delta G ^ { \circ } > 0 ; K _ { \mathrm { eq } } < 1 {/tex}

B

{tex} \Delta G ^ { \circ } > 0 ; K _ { \mathrm { eq } } > 1 {/tex}

C

{tex}\Delta G^{\circ}<0:K_{eq}>1{/tex}

D

{tex} \Delta G ^ { \circ } < 0 ; K _ { eq } < 1 {/tex}

Explanation


Q 5.    

Correct4

Incorrect-1

The number of electrons delivered at the cathode during electrolysis by a current of 1 ampere in 60 seconds is (charge on electron {tex} \left. = 1.60 \times 10 ^ { - 19 } \mathrm { C } \right) {/tex}

A

{tex} 6 \times 10 ^ { 23 } {/tex}

B

{tex} 6 \times 10 ^ { 20 } {/tex}

{tex} 3.75 \times 10 ^ { 20 } {/tex}

D

{tex} 7.48 \times 10 ^ { 23 } {/tex}

Explanation





Q 6.    

Correct4

Incorrect-1

Zinc can be coated on iron to produce galvanized iron but the reverse is not possible. It is because

A

zinc is lighter than iron

B

zinc has lower melting point than iron

C

zinc has lower negative electrode potential than iron

zinc has higher negative electrode potential than iron.

Explanation


Q 7.    

Correct4

Incorrect-1

The pressure of {tex} \mathrm { H } _ { 2 } {/tex} required to make the potential of {tex} \mathrm { H } _ { 2 } {/tex} -electrode zero in pure water at {tex} 298\,\mathrm { K } {/tex} is

A

{tex} 10 ^ { - 10 } \mathrm { atm } {/tex}

B

{tex} 10 ^ { - 4 } \mathrm { atm } {/tex}

{tex} 10 ^ { - 14 } \mathrm { atm } {/tex}

D

{tex} 10 ^ { - 12 } \mathrm { atm } {/tex}

Explanation


Q 8.    

Correct4

Incorrect-1

A device that converts energy of combustion of fuels like hydrogen and methane, directly into electrical energy is known as

A

dynamo

B

Ni-Cd cell

fuel cell

D

electrolytic cell.

Explanation

Q 9.    

Correct4

Incorrect-1

When 0.1 mol {tex} \mathrm { MnO } _ { 4 } ^ { 2 - } {/tex} is oxidised the quantity of electricity required to completely oxidise {tex} \mathrm { MnO } _ { 4 } ^ { 2 - } {/tex} to {tex} \mathrm { MnO } _ { 4 } ^ { - } {/tex} is

A

{tex} \mathrm { 96500 \ C } {/tex}

B

{tex} \mathrm{ 2 \times 96500\ C } {/tex}

{tex} \mathrm { 9650\ C } {/tex}

D

{tex} \mathrm { 96.50\ C } {/tex}

Explanation


Q 10.    

Correct4

Incorrect-1

The weight of silver (at. wt. = 108) displaced by a quantity of electricity which displaces {tex}5600\ \mathrm { mL } {/tex} of {tex} \mathrm { O } _ { 2 } {/tex} at STP will be

A

5.4 g

B

10.8 g

C

54.0 g

108.0 g

Explanation


Q 11.    

Correct4

Incorrect-1

At {tex}\mathrm {25^\circ\,C}{/tex} molar conductance of 0.1 molar aqueous solution of ammonium hydroxide is {tex}\mathrm {9.54 \ ohm^{-1} cm^2\ mol^{-1}}{/tex} and at infinite dilution its molar conductance is {tex}\mathrm {238\ ohm^{-1}\ cm^2\ mol^{-1}}{/tex}. The degree of ionisation of ammonium hydroxide at the same concentration and temperature is

4.008{tex} \% {/tex}

B

40.800{tex} \% {/tex}

C

2.080{tex} \% {/tex}

D

20.800{tex} \% {/tex}

Explanation



Q 12.    

Correct4

Incorrect-1

A button cell used in watches function as following:

{tex} \mathrm { Zn } _ { ( s ) } + \mathrm { Ag } _ { 2 } \mathrm { O } _ { ( s ) } + \mathrm { H } _ { 2 } \mathrm { O } _ { ( l ) } \rightleftharpoons 2 \mathrm { Ag } _ { ( s ) } +\mathrm {Zn^{2+}_{(aq)}} +2 \mathrm { OH } _ { ( a q ) } {/tex}

If half cell potentials are

{tex} \mathrm { Zn } ^ { 2 + }_{( aq)} + 2 e ^ { - } \rightarrow \mathrm { Zn } _ { ( s ) } ; E ^ { \circ } = - 0.76 \mathrm { V } {/tex}
{tex} \mathrm { Ag_2 {O_{(s)}}} +\mathrm {H_2O}_{(l)}+ 2 e ^ { - } \rightarrow \mathrm { 2Ag } _ { ( s ) } + \mathrm {2OH^-}_{(aq)}, E ^ { \circ } = - 0.34 \mathrm { V } {/tex}

The cell potential will be

A

{tex} 0.84\,\mathrm { V } {/tex}

B

{tex} 1.34\,\mathrm { V } {/tex}

{tex} 1.10\,\mathrm { V } {/tex}

D

{tex} 0.42\,\mathrm { V } {/tex}

Explanation

Q 13.    

Correct4

Incorrect-1

A hydrogen gas electrode is made by dipping platinum wire in a solution of HCl of pH = 10 and by passing hydrogen gas around the platinum wire at one atm pressure. The oxidation potential of electrode would be

A

{tex} 0.118\,\mathrm { V } {/tex}

B

{tex}1.18\, \mathrm { V } {/tex}

C

{tex}0.059\,\mathrm { V } {/tex}

{tex} 0.59\,\mathrm { V } {/tex}

Explanation


Q 14.    

Correct4

Incorrect-1

Consider the half-cell reduction reaction
{tex} \mathrm { Mn } ^ { 2 + } + 2 e ^ { - } \rightarrow \mathrm { Mn } , E ^ { \circ } = - 1.18 \mathrm { V } {/tex}
{tex} \mathrm { Mn } ^ { 2 + } \rightarrow \mathrm { Mn } ^ { 3 + } + e ^ { - } , E ^ { \circ } = - 1.51 \mathrm { V } {/tex}
The {tex} E ^ { \circ } {/tex} for the reaction {tex} 3 \mathrm { Mn } ^ { 2 + } \rightarrow \mathrm { Mn } ^ { 0 } + 2 \mathrm { Mn } ^ { 3 + }, {/tex} and possibility of the forward reaction are respectively

A

{tex} - 4.18 \mathrm { V } {/tex} and yes

B

{tex} + 0.33 \mathrm { V } {/tex} and yes

C

{tex} + 2.69 \mathrm { V } {/tex} and no

{tex} - 2.69 \mathrm { V } {/tex} and no

Explanation


Q 15.    

Correct4

Incorrect-1

How many gram of cobalt metal will be deposited when a solution of cobalt (II) chloride is electrolyzed with a current of 10 amperes for 109 minutes {tex} ( 1 \text { Faraday } = 96,500 \mathrm { C } ; \text { Atomic } {/tex} {tex} \text { mass of } \mathrm { Co } = 59 \mathrm { u } ) {/tex}

A

4.0

20.0

C

40.0

D

0.66

Explanation

Q 16.    

Correct4

Incorrect-1

Limiting molar conductivity of {tex}\mathrm { NH_4OH\,[i.e.\ \wedge^{\circ}_{m(NH_4OH)}]}{/tex} is equal to

A

{tex}\mathrm {\wedge^{\circ}_{m(NH_4Cl)}+\wedge^{\circ}_{m(NaCl)}-\wedge^{\circ}_{m(NaOH)}}{/tex}

B

{tex}\mathrm {\wedge^{\circ}_{m(NaOH)}+\wedge^{\circ}_{m(NaCl)}-\wedge^{\circ}_{m(NH_4Cl)}}{/tex}

C

{tex}\mathrm {\wedge^{\circ}_{m(NH_4OH)}+\wedge^{\circ}_{m(NH_4Cl)}-\wedge^{\circ}_{m(HCl)}}{/tex}

{tex}\mathrm {\wedge^{\circ}_{m(NH_4Cl)}+\wedge^{\circ}_{m(NaOH)}-\wedge^{\circ}_{m(NaCl)}}{/tex}

Explanation

Q 17.    

Correct4

Incorrect-1

Standard reduction potentials of the half reactions are given below:
{tex} \mathrm { F } _ { 2 ( g ) } + 2 e ^ { - } \rightarrow 2 \mathrm { F } ^ { - } _{( a q )} ; E ^ { \circ } = + 2.85\ \mathrm { V } {/tex}
{tex} \mathrm { Cl } _ { 2 ( \mathrm { g } ) } + 2 e ^ { - } \rightarrow 2 \mathrm { Cl } _ { ( a q ) } ^ { - } ; E ^ { \circ } = + 1.36\ \mathrm { V } {/tex}
{tex} \mathrm { Br } _ { 2 ( l ) } + 2 e ^ { - } \rightarrow 2 \mathrm { Br } _ { ( a q ) } ^ { - } ; E ^ { \circ } = + 1.06\ \mathrm { V } {/tex}
{tex} \mathrm { I } _ { 2 ( s ) } + 2 e ^ { - } \rightarrow 2 \mathrm { I } _ { ( a q ) } ^ { - } ; E ^ { \circ } = + 0.53\ \mathrm { V } {/tex}
The strongest oxidising and reducing agents 23 respectively are

{tex} \mathrm { F } _ { 2 } {/tex} and {tex} \mathrm { I }^- {/tex}

B

{tex} \mathrm { Br } _ { 2 } {/tex} and {tex} \mathrm { Cl } ^ { - } {/tex}

C

{tex} \mathrm { Cl } _ { 2 } {/tex} and {tex} \mathrm { Br }^- {/tex}

D

{tex} \mathrm { Cl } _ { 2 } {/tex} and {tex} \mathrm { I } _ { 2 } {/tex}

Explanation


Q 18.    

Correct4

Incorrect-1

Molar conductivities {tex}(\wedge_m^\circ){/tex} at infinite dilution of {tex}\mathrm {NaCl, HCl}{/tex} and {tex}\mathrm {CH_3COONa}{/tex} are 126.4,425.9 and 91.0 {tex}\mathrm {S\ cm^2\ mol^{-1}}{/tex} respectively. {tex}(\wedge^\circ_m){/tex} for {tex}\mathrm {CH_3COOH}{/tex} will be.

A

{tex}425.5\, \mathrm { S } \,\mathrm{ cm } ^ { 2 } \mathrm { mol } ^ { - 1 } {/tex}

B

{tex}180.5\, \mathrm { S\,cm } ^ { 2 } \mathrm { mol } ^ { -1 } {/tex}

C

{tex}290.8 \,\mathrm { S } \,\mathrm { cm } ^ { 2 } \mathrm { mol } ^ { - 1 } {/tex}

{tex}390.5\, \mathrm { S\,cm } ^ { 2 } \mathrm { mol } ^ { - 1 } {/tex}

Explanation


Q 19.    

Correct4

Incorrect-1

The Gibb's energy for the decomposition of {tex} \mathrm { Al } _ { 2 } \mathrm { O } _ { 3 } {/tex} at {tex} 500 ^ { \circ } \mathrm { C } {/tex} is as follows

{tex} \frac { 2 } { 3 } \mathrm { Al } _ { 2 } \mathrm { O } _ { 3 } \rightarrow \frac { 4 } { 3 } \mathrm { Al } + \mathrm { O } _ { 2 } {/tex}

{tex} \Delta _ { r } G = + 960\ \mathrm { kJ }\ \mathrm { mol } ^ { - 1 } {/tex}

The potential difference needed for the electrolytic reduction of aluminium oxide {tex} \left( \mathrm { Al } _ { 2 } \mathrm { O } _ { 3 } \right) {/tex} at {tex} 500 ^ { \circ } \mathrm { C } {/tex} is at least

A

{tex} 4.5\,\mathrm { V } {/tex}

B

{tex}3.0 \,\mathrm { V } {/tex}

{tex}2.5\, \mathrm { V } {/tex}

D

{tex} 5.0\,\mathrm { V } {/tex}

Explanation


Q 20.    

Correct4

Incorrect-1

Standard electrode potential of three metals {tex} X , Y {/tex} and {tex} Z {/tex} are {tex} - 1.2\ \mathrm { V } , + 0.5\ \mathrm { V } {/tex} and {tex} - 3.0\ \mathrm { V } {/tex} respectively. The reducing power of these metals will be

A

{tex} Y > Z > X {/tex}

B

{tex} Y > X > Z {/tex}

{tex} Z > X > Y {/tex}

D

{tex} Y > Y > Z {/tex}

Explanation


Q 21.    

Correct4

Incorrect-1

The electrode potential for
{tex}\mathrm{Cu^{2+}_{(aq)}+e^-\rightarrow Cu^+_{(aq)}}{/tex} and {tex}Cu^{+}_{(aq)}+e^-\rightarrow Cu_{(s)}{/tex}
are + 0.15 V and + 0.50 V respectively. The value of {tex}E^\circ_{cu^{2+}/Cu}{/tex} will be

A

{tex} 0.500\,\mathrm { V } {/tex}

{tex} 0.325\,\mathrm { V } {/tex}

C

{tex} 0.650\,\mathrm { V } {/tex}

D

{tex} 0.150\,\mathrm { V } {/tex}

Explanation


Q 22.    

Correct4

Incorrect-1

Standard electrode potential for {tex} \mathrm { Sn } ^ { 4 + } / \mathrm { Sn } ^ { 2 + } {/tex} couple is {tex} + 0.15 \mathrm { V } {/tex} and that for the {tex} \mathrm { Cr } ^ { 3 + } / \mathrm { Cr } {/tex} couple is {tex} - 0.74 \mathrm { V } {/tex} . These two couples in their standard state are connected to make a cell. The cell potential will be

A

{tex} + 1.19 \,\mathrm { V } {/tex}

{tex} + 0.89\, \mathrm { V } {/tex}

C

{tex} + 0.18 \,\mathrm { V } {/tex}

D

{tex} + 1.83 \,\mathrm { V } {/tex}

Explanation

Q 23.    

Correct4

Incorrect-1

A solution contains {tex} \mathrm { Fe } ^ { 2 + } , \mathrm { Fe } ^ { 3 + } {/tex} and {tex}\mathrm {I^-}{/tex} ions. This solution was treated with iodine at {tex} 35 ^ { \circ } \mathrm { C } . E ^ { \circ } {/tex} for {tex} \mathrm { Fe } ^ { 3 + } / \mathrm { Fe } ^ { 2 + } \mathrm { is } + 0.77\ \mathrm { V } {/tex} and {tex} E ^ { \circ } {/tex} for {tex} \mathrm{{ I } _ { 2 } / 2 I^-} = 0.536\ \mathrm { V } {/tex} . The favourable redox reaction is

A

{tex} \mathrm { I } _ { 2 } {/tex} will be reduced to {tex} \mathrm { I^- } {/tex}

B

there will be no redox reaction

{tex} \mathrm { I } ^ { - } {/tex} will be oxidised to {tex} \mathrm { I } _ { 2 } {/tex}

D

{tex} \mathrm { Fe } ^ { 2 + } {/tex} will be oxidised to {tex} \mathrm { Fe } ^ { 3 + } {/tex}

Explanation



Q 24.    

Correct4

Incorrect-1

For the reduction of silver ions with copper metal, the standard cell potential was found to be {tex} + 0.46\ \mathrm { V } {/tex} at {tex} 25 ^ { \circ } \mathrm { C } {/tex} . The value of standard Gibb's energy, {tex} \Delta G ^ { \circ } {/tex} will be {tex} \left( \mathrm { F } = 96500 \,\mathrm { C } \,\mathrm { mol } ^ { - 1 } \right) {/tex}

{tex} - 89.0\ \mathrm{ kJ } {/tex}

B

{tex} - 89.0\ \mathrm { J } {/tex}

C

{tex} - 44.5\ \mathrm { kJ } {/tex}

D

{tex} - 98.0\ \mathrm { kJ } {/tex}

Explanation


Q 25.    

Correct4

Incorrect-1

An increase in equivalent conductance of a strong electrolyte with dilution is mainly due to

increase in ionic mobility of ions

B

{tex}100\, \% {/tex} ionisation of electrolyte at normal dilution

C

increase in both i.e. , number of ions and ionic mobility of ions

D

increase in number of ions.

Explanation