JEE Chemistry - Electrochemistry Chapter Sample Question Paper With Answer Key
Exam Duration: 60 Mins Total Questions : 50
When an aqueous solution of potassium chloride is electroysed using platinum cathode and silver anode,the substances formed at the electrodes are
- (a)
hydrogen and AgCl
- (b)
hydrogen and chloride
- (c)
potassium and chlorine
- (d)
oxygen and chlorine
The products obtained at the electrodes by the electrolysis of copper sulphate solution using copper electrodes are
- (a)
Cu and SO42-
- (b)
OH- and H2
- (c)
O2 and H2
- (d)
NONE OF THESE
Electrochemical reaction at the anode is oxidation.Which one of the following is not an anodic reaction?
- (a)
\(Cl\longrightarrow Cl+e\)
- (b)
\(Fe^{3+}+e^-\longrightarrow Fe^{2+}\)
- (c)
\(Cu\longrightarrow cu^{2+} +2e\)
- (d)
\(Zn=Zn^{2+} 2e^-\)
Cells containing a solution of mercuric perchlorate(i),mercury nitrate (ii),and mercurous perchlorate(iii),were connected ,in series so that the same quantity of electrocity passes through them,The amount of mercury obtained at the cathode is the same
- (a)
in all the cells
- (b)
in cells(i) and (ii) but more in cell(iii)
- (c)
in cells(i) and (iii) but more in cell(ii)
- (d)
in cells(ii) and (iii) but more in cell(i)
A current liberates 0.504g of hydrogen in 2 hours.How many grams of copper can be liberated by the same current flowing for the same time in cuprous cyanide solution?
- (a)
12.7
- (b)
15.9
- (c)
31.8
- (d)
63.6
2.5 faraday of electricity are passed through a solution of CuSO4 .The number of gram equivalent of Cu deposited on the anode would be
- (a)
0
- (b)
2
- (c)
1.25
- (d)
1.24
Which one of the following reactions occurs at the cathode?
- (a)
hydrolysis
- (b)
oxidation
- (c)
reduction
- (d)
none
Which of the following reaction takes place at the anode during the electrolysis of fused sodium chloride?
- (a)
oxidation of chloride ion
- (b)
oxidation of sodium ion
- (c)
reduction of chlorine atom
- (d)
reduction of sodium ion
A half reaction is one that
- (a)
goes only half way to completion
- (b)
involves only half-mole of electrolyte
- (c)
consumes only half a unit of electricity
- (d)
takes place at one electrode
The following reaction describes the rusting of iron.
4Fe+3O2\(\longrightarrow\) Fe3+ +6O2-
Which one of the following statements is incorrect?
- (a)
This is an example of redox reaction
- (b)
Metalic iron is reduced to Fe3+
- (c)
Fe3+ is an oxidizing agent
- (d)
Metalic iron is a reducing agent
When a copper wire is immersed in silver nitrate solution ,the colour of the solution becomes blue,because copper
- (a)
Oxidises silver into silver ions
- (b)
reduces silver ions in the solution
- (c)
is reduced to copper(i)
- (d)
is oxidised to copper(i)
Standard electrode potential,E0 values in volts,of a few metals are given below
Mg2+/Mg=-2.37,Zn2+/Zn=-0.76;Sn2+/Sn =-0.14
Which one of the following conclusions drawn from Which one of the following conclusions drawn from these values is wrong?
- (a)
Magnesium is a stronger reducing agent than zinc
- (b)
Zinc is a stronger oxidising agent than Sn(ii) ion
- (c)
Zinc is a stronger reducing agent than tin
- (d)
Sn(ii) ion is a stronger oxidising agent than tin
The half cell potential at 298k for the reaction
Cu2+ (aq) +2e\(\longrightarrow\) Cu(s) with [Cu2+]=5.0M and Eo for Cu2+/Cu=0.34 volt,is found to be
- (a)
0.32v
- (b)
0.34v
- (c)
0.36v
- (d)
-0.34v
Which one of the statement is wrong?
- (a)
In primary cells,the reaction occurs only once and then becomes dead over a period of time
- (b)
secondary cells can be recharged by passing a current through them,so that they can be used again
- (c)
nickel battery is an example of secondary cell
- (d)
mercury cell is an example of secondary cell
Saturated solution of KNO3 is used to make salt bridge because
- (a)
velocity of K+ is greaterv than that of NO-3
- (b)
velocity of NO-3 is greater than that of K+
- (c)
velocities of both K+ and NO-3 are nearly the same
- (d)
KNO3 is highly soluble in water
At infinite dilution ,the molar conductivity in 5 cm2 mol-1 units for various electrolytes is given as HCl =426,NaCl=126,CH3COONa=91.From these data ,the calculated value of molar conductivity at infinite dilution for CH3COOH will be
- (a)
391
- (b)
335
- (c)
300
- (d)
217
The approximate mass of copper deposited on the cathode when a current of 0.2 ampere is passed through a solution of copper sulphate for 10 minutes.E copper=31.78
- (a)
0.04g
- (b)
0.03g
- (c)
0.02g
- (d)
0.01g
The time required in seconds to coat a metal surface of 80cm2 with a 0.005mm thick layer by passing a current of 3 ampere is
- (a)
100s
- (b)
125s
- (c)
1200s
- (d)
150s
The charge in coulombs of N-3 ion is
- (a)
\(96500\)
- (b)
\(4.8\times10^{19}\)
- (c)
\(4.8\times10^{-10}\)
- (d)
\(1.6\times10^{-19}\)
The quantity of electricity required required to reduce 12.3g of nitrobenzene to aniline asuming 50% current efficiency is
- (a)
57900 C
- (b)
28950 C
- (c)
115800 C
- (d)
231600 C
The resistance of 0.1N solution of electrolyte at 330K is 100 ohm .The specific conductance of the solution is (cell constant =1 cm-1)
- (a)
10-2 ohm-1 cm-1
- (b)
10-3 ohm-1 cm-1
- (c)
10-4 ohm-1 cm-1
- (d)
NONE OF THE ABOVE
The resistance of 0.01 N NaCl solution at 25o c is 200\(\omega\) .Cell constant of the conductivity cell is unity.the equivalent conductance of the solution would be
- (a)
0.5 ohm-1 cm2 mol-1
- (b)
1.5 ohm-1 cm2 mol-1
- (c)
2.5 ohm-1 cm2 mol-1
- (d)
NONE OF THE ABOVE
How many columbs are required for the oxidation of one mole of H2O to O2 ?
- (a)
\(1.93\times10^2\)
- (b)
\(1.93\times10^4\)
- (c)
\(1.93\times10^5\)
- (d)
\(1.93\times10^6\)
The value of K for the reaction \(CH_3COOH+C_2H_5OH\longrightarrow CH_3COOC_2H_5+H_2O\) IS 4 at 250C .The value of G for the above reaction would be approximately
- (a)
-2.5 KJ mol-1
- (b)
-3.5KJ mol-1
- (c)
-4.5KJ mol-1
- (d)
NONE OF THE ABOVE
The e.m.f of the cell formed by E0 Fe2+/Fe=-0.45 v would be approximately
- (a)
0.25 v
- (b)
0.22 v
- (c)
0.26 v
- (d)
None of the above
The standard reduction potential E0 Zn2+/Zn is -0.76 v and E0 Fe2+/Fe=-0.45 v Daniel cell is
- (a)
+1.10v
- (b)
-1.10v
- (c)
-0.76
- (d)
-0.42
On passing 0.1 Faraday of current through a copper sulphate solution(2.0molar),the amount of copper deposited at the cathode:
- (a)
2.0 mol
- (b)
1.0 mol
- (c)
0.05 mol
- (d)
0.25 mol
The best electrical conductor among the following is
- (a)
0.01 M NaCl
- (b)
0.10 M ethanol
- (c)
0.10 M CH3COOH
- (d)
0.10 M sucrose
If \(\phi\) denotes reduction potential,then which is true
- (a)
E0 cell=\(\phi\) right-\(\phi\) left
- (b)
E0 cell=\(\phi\) left+\(\phi\) right
- (c)
E0 cell=\(\phi\) left-\(\phi\) right
- (d)
E0 cell=(\(\phi\) left-\(\phi\) right)
What will be the emf for the given cell? Pt|H2(P1)|H+ (aq) || H2(P2) Pt
- (a)
\(\frac{RT}{F} log \frac{P_1}{p_2}\)
- (b)
\(\frac{RT}{2F} log \frac{P_1}{p_2}\)
- (c)
\(\frac{RT}{P} log \frac{P_1}{p_2}\)
- (d)
NONE OF THESE
Nernst's equation is
- (a)
\(E=E0 -\frac{RT}{nF}In\frac{red}{OX}\)
- (b)
\(E=E0 +\frac{RT}{nF}In\frac{red}{OX}\)
- (c)
\(E_0=E -\frac{RT}{nF}In\frac{red}{OX}\)
- (d)
\(E_0=E+\frac{RT}{nF}In\frac{red}{OX}\)
What is the emf of the cell? Cr|Cr3+(1.0 M) || Cq2+(1.0M)||Cq2+ (0.1M)|Cq (E0 for Cr3+|Cr =-0.74 volt and E0 for Co2+/Co=-0.28 volt)
- (a)
-1.02 volt
- (b)
-0.46 volt
- (c)
+0.46 volt
- (d)
1.66 volt
The reaction 1/2H2(g)+AgCl(s)\(\longrightarrow \) H+(aq)+Cl-(aq)+Ag(s) occurs in the galvanic cell
- (a)
Ag/AgCl(s) KCl soln//AgNo3(aq)/Ag
- (b)
Pt/H2(g) HCl soln //AgNO3(aq)/Ag
- (c)
Pt/H2(g) HCl soln//AgCl(s)/Ag
- (d)
Pt/H2(g) KCl soln//AgCl(s)/Ag
The conductivity of a 0.01 N solution is found to be 0.005 \({ \Omega }^{ -1 }{ cm }^{ 2 }\). The equivalent conductivity of the solution will be
- (a)
\(5\times { 10 }^{ -2 }{ \Omega }^{ -1 }{ cm }^{ 2 }{ equiv }^{ -1 }\)
- (b)
\(5.00\times { 10 }^{ -3 }{ \Omega }^{ -1 }{ cm }^{ 2 }\)
- (c)
\(500\quad { \Omega }^{ -1 }{ cm }^{ 2 }{ equiv }^{ -1 }\)
- (d)
\(0.5\quad { \Omega }^{ -1 }{ cm }^{ 2 }{ equiv }^{ -1 }\)
At \({ 25 }^{ \circ }C\), the molar conductances at infinite dilution for the strong electrolytes NaOH, NaCI and BaCI2 are \(248\times { 10 }^{ -4 },\quad 126\times { 10 }^{ -4 }\)and \(280\times { 10 }^{ -4 }\quad S{ m }^{ 2 }\quad { mol }^{ -1 }\)respectively. \({ \wedge }_{ m }^{ 0 }\quad Ba(OH)_{ 2 }\quad in\quad S{ m }^{ 2 }\quad { mol }^{ -1 }\) is
- (a)
\(52.4\times { 10 }^{ -4 }\)
- (b)
\(524\times { 10 }^{ -4 }\)
- (c)
\(40.4\times { 10 }^{ -4 }\)
- (d)
\(262\times { 10 }^{ -4 }\)
An electrochemical cell can behave like an electrolytic cell when
- (a)
Ecell = 0
- (b)
Ecell > Eext
- (c)
Eext > Ecell
- (d)
E cell = Eext
Which cell will measure standard electrode potential of copper electrode?
- (a)
\(Pt(s)\ |{ H }_{ 2 }(g,\ 0.1\ bar)|\ { H }^{ + }(aq,\ 1M)\ ||\ { Cu }^{ 2+ }(aq,\ 1\ M)\ |\ Cu\)
- (b)
\(Pt(s)\ |{ H }_{ 2 }(g,\ 1\ bar)|\ { H }^{ + }(aq,\ 1M)\ ||\ { Cu }^{ 2+ }(aq,\ 2\ M)\ |\ Cu\)
- (c)
\(Pt(s)\ |{ H }_{ 2 }(g,\ 1\ bar)|\ { H }^{ + }(aq,\ 1M)\ ||\ { Cu }^{ 2+ }(aq,\ 1\ M)\ |\ Cu\)
- (d)
\(Pt(s)\ |{ H }_{ 2 }(g,\ 1\ bar)|\ { H }^{ + }(aq,\ 0.1M)\ ||\ { Cu }^{ 2+ }(aq,\ 1\ M)\ |\ Cu\)
The standard electrode potentials for the reactions,
\({ Ag }^{ + }(aq)+{ e }^{ - }\longrightarrow Ag(s)\) \({ S }n^{ 2+ }(aq)\ +\ 2{ e }^{ - }\longrightarrow Sn(s)\) at \({ 25 }^{ \circ }C\) are 0.80 V and -0.14 V, respectively.
The emf of the cell, \(Sn\ |\ { S }n^{ 2+ }(1M)\ ||\ Ag^{ + }(1M)\ |Ag\ \) is
- (a)
0.48 V
- (b)
0.80 V
- (c)
1.08 V
- (d)
0.94 V
\({ E }_{ \left( { Ni }^{ 2+ }/Ni \right) }^{ \circ }=-0.25V,\)
\({ E }_{ (A{ u }^{ 3+ }/Au) }^{ \circ }=1.50V.\)
The emf of the voltaic cell, \(\frac { Ni }{ { Ni }^{ 2+ } } \) (1.0M) || Au3+(1.0 M) | Au is
- (a)
1.25 V
- (b)
-1.75 V
- (c)
1.75 V
- (d)
2.0 V
Calculate the electrode potential at copper electrode dipped in a 0.1 M solution of copper sulphate at \({ 25 }^{ \circ }C\). The standard electrode potential of Cu 2+/Cu system is 0.34 V at 298 K.
- (a)
+0.31045
- (b)
-0.31045
- (c)
-0.43892 V
- (d)
-0.23682 V
Calculate the emf of the following cell at \({ 25 }^{ \circ }C\) \(\underset { 2\ atm }{ { Pt\ H }_{ 2 } } |HCI|\underset { 10\ atm }{ { H }_{ 2 }\ Pt } \)
- (a)
-0.0206 V
- (b)
+0.0206 V
- (c)
+0.8056 V
- (d)
-0.8056 V
On the basis of electrochemical theory of aqueous corrosion, the reaction occurring at the cathode is
- (a)
O2(g) + 4H+(aq) + 4e- \(\longrightarrow \) 2H2O(l)
- (b)
H2(g) + 2OH-(aq) \(\longrightarrow \) 2H2O(l) + 2e-
- (c)
Fe2(AQ) + 2e- \(\longrightarrow \) Fe(s)
- (d)
Fe3+(aq) + e- \(\longrightarrow \) Fe2+(aq)
For the following cell with hydrogen electrodes at two different pressures p1 and p2. \(\underset { p1 }{ Pt\left( { H }_{ 2 } \right) } |\underset { 1M }{ { H }^{ + }\left( aq \right) } |\underset { p2 }{ Pt\left( { H }_{ 2 } \right) } \) emf is given by
- (a)
\(\frac { RT }{ F } { log }_{ e }\frac { { p }_{ 1 } }{ { p }_{ 2 } } \)
- (b)
\(\frac { RT }{ 2F } { log }_{ e }\frac { { p }_{ 1 } }{ { p }_{ 2 } } \)
- (c)
\(\frac { RT }{ F } { log }_{ e }\frac { { p }_{ 2 } }{ { p }_{ 1 } } \)
- (d)
\(\frac { RT }{ 2F } { log }_{ e }\frac { { p }_{ 2 } }{ { p }_{ 1 } } \)
Calculate the potential corresponding to the following cell.
Given \(Pt|{ Co }^{ 2+ }(2.0M),{ Co }^{ 3+ }(0.01M)||{ Cr }^{ 3+ }(0.5M),\quad { Cr }_{ 2 }{ O }_{ 7 }^{ 2- }(4.0M),{ H }^{ + }(1.5M)|Pt\)\({ E }_{ { Co }^{ 2+ }/{ Co }^{ 3+ } }^{ \circ }=-1.82V,\quad { E }_{ { Cr }_{ 2 }{ O }_{ 7 }^{ 2- }/{ Cr }^{ 3+ } }^{ \circ }=+1.33V\)
- (a)
-0.32 V
- (b)
+0.32 V
- (c)
0.44 V
- (d)
+0.44 V
What flows in the internal circuit of a galvanic cell ?
- (a)
Ions
- (b)
Electrons
- (c)
Electricity
- (d)
Atoms
Resistance of 0.2 M solution of an electrolyte is 50 \({ \Omega }\).The specific conductance of the solution of 0.5 M solution of same electrolyte is 1.4 Sm-1 and resistance of same solution of the same electrolyte is 280 \({ \Omega }\). The molar conductivity of 0.5 M solution of the electrolyte in Sm2 mol-1 is
- (a)
5 \(\times\) 10-4
- (b)
5 \(\times\) 10-3
- (c)
5 \(\times\) 103
- (d)
5 \(\times\) 102
The reduction potential of hydrogen half-cell will be negative if
- (a)
p(H2) = 1 atm and [H+] = 2.0 M
- (b)
p(H2) = 1 atm and [H+] = 1.0 M
- (c)
p(H2) = 2 atm and [H+] = 1.0 M
- (d)
p(H2) = 2 atm and [H+] = 2.0 M
In a cell that utilizes the reaction Zn(s)+2H+(aq) \(\longrightarrow \) Zn2+(aq) + H2(g) addition of H2SO 4 to cathode compartment will
- (a)
lower the E and shift the equilibrium to the left
- (b)
lower the E and shift the equilibrium to the right
- (c)
increase the E and shift the equilibrium to the right
- (d)
increase the E and shift the equilibrium to the left
For the redox reaction, \(Zn(s)+C{ u }^{ 2+ }(0.1M)\longrightarrow { Zn }^{ 2+ }(1M)+Cu(s)\) taking place in a cell, \({ E }^o_{ cell }\) is 1.10 v. \({ E }_{ cell }\) for the cell will be \(\left( 2.303\frac { RT }{ F } =0.0591 \right) \)
- (a)
2.14 V
- (b)
1.80 V
- (c)
1.07 V
- (d)
0.82 V
For a cell reaction involving a two electron change, the standard emf of the cell is found to be 0.295V at \(25^{ \circ }C\) . The equilibrium constant of the reaction at \(25^{ \circ }C\) will be
- (a)
1 \(\times\) 10-10
- (b)
29.5 \(\times\) 10-2
- (c)
10
- (d)
1 \(\times\) 1010