Chapter: Electrochemistry
Topic: Nernst Equation
Content: MCQ Questions & Solutions
Source: CSIR NET, GATE etc. Exams
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Q1. Given:
A. Fe(OH)2(s) + 2e- → Fe(s) + 2OH-(aq);
Eº = -0.877 V
B. Al3+(aq) + 3e- →
Al(s); Eº = -1.66
C. AgBr(aq) + e- → Ag(s) + Br-(aq);
Eº = 0.071 V
The overall reaction for the cells in
the direction of spontaneous change would be
[NET June 2014]
(a) Cell with A and B : Fe Reduced
Cell with A and C : Fe Reduced
(b) Cell with A and B : Fe Reduced
Cell with A and C : Fe Oxidized
(c) Cell with A and B : Fe Oxidized
Cell with A and C : Fe Oxidized
(d) Cell with A and B : Fe Oxidized
Cell with A and C : Fe Reduced
Q2. For
the cell reaction, Sn(s) + Sn4+(aq) ⇌ 2Sn2+(aq),
separate electrode reactions would be written with the respective standard
electrode potential data at 25ºC as
Sn4+(aq) + 2e- → Sn2+(aq); Eº = +0.15 V
Sn2+(aq) + 2e- → Sn(s); Eº = -0.14 V
When RT/F is given as 25.7 mV, logarithm
of the equilibrium constant (ln K) is
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(a) 22.6
(b) 226
(c) 2.26
(d) 2.26 x 10-1
Q3. Fuel
cells provide clean electrical energy to a variety of applications including
automobiles and stationary power sources. Normally hydrogen combines with
oxygen to give electrical energy and water. If we use butane instead of
hydrogen at 1.0 bar and 298 K, the following reaction occurs:
C4H10(g)
+ 13/2 O2(g) → 4 CO2(g) + 5 H2O(l)
If the change in Gibbs free energy of
this reaction is 2746.06 KJmol-1, involving 26 electrons, its open
circuit voltage is
[NET Dec 2014]
(a) 1.55 V
(b) 1.09 V
(c) 3.15 V
(d) 2.06 V
Q4. Dominant
contribution to the escaping tendency of a charged particle with uniform
concentration in a phase, depends on
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(a) chemical potential of that phase
(b) electric potential of that phase
(c) thermal energy of that phase
(d) gravitational potential of that phase
Q5. The
correct ΔG for the cell reaction involving steps
Zn(s) → Zn2+(aq)
+ 2e-
Cu2+(aq) + 2e- → Cu(s) is
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Q6. The
temperature dependence of an electrochemical cell potential is
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(a) ΔG/nFT
(b) ΔH/nF
(c) ΔS/nF
(d) ΔS/nFT
Q7. Conductometric
titration of a strong acid with a strong alkali (MOH) shows linear fall of
conductance up to neutralization point because of
[NET June 2015]
(a) formation of water
(b) Increase in alkali concentration
(c) faster moving H+ being replaced by
slower moving M+
(d) neutralization of acid
Q8. Given
that E°(Cl2|Cl-) = 1.35 V and Ksp (AgCl) = 10-10 at 25°C,
E° corresponding to the electrode reaction
1/2 Cl2(g)
+ Ag+(solution) + e- → AgCl(s)
is [2.303RT/F = 0.06 V]
[NET Dec 2015]
(a) 0.75 V
(b) 1.05 V
(c) 1.65 V
(d) 1.95 V
Q9. The
standard EMF of the cell
Pt, H2(g)
| HCl(solution) || AgCl(s), Ag(s)
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(a) increase with T
(b) decrease with T
(c) remains unchanged with T
(d) decreases with HCl
Q10. The
standard electrode potential E° at a fixed temperature and in a given medium is
dependent on
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(a) only on electrode composition
(b) the electrode composition and the extent of
the reaction
(c) the extent of the electrode reaction only
(d) the electrode reaction and the electrode
composition
Q11. On titrating conductometrically a NaOH solution with a mixture
of HCl and CH3COOH solutions, plot the volume of mixed acid added (b) in y-axis
against the conductance (a) in x-axis is expected to look like
[NET June 2016]
Q12. The ionic mobilities of NH4+ and HCO3-
are 6 x 10-4 V-1s-1 and 5 x 10-4 V-1s-1
respectively. The transport numbers of NH4+ and HCO3-
are, respectively
[NET Dec 2016]
(a) 0.545 and 0.455
(b) 0.455 and 0.545
(c) 0.090 and 0.910
(d) 0.910 and 0.090
Q13. Given,
(i)
Zn + 4 NH3 → Zn(NH3)42+
+ 2e-; Eº = 1.03 V
(ii) Zn →
Zn2+ + 2e-; Eº = 0.763 V
The formation constant of the complex [Zn(NH3)42+] is approximately
(2.303 RT/F = 0.0591)
[NET Dec 2016]
(a) 1 x 105
(b) 1 x 107
(c) 1 x 109
(d) 1 x 1012
Answer Key
Q1.b Q2.a Q3.b Q4.b Q5.d Q6.c Q7.c Q8.d Q9.b Q10.d Q11.c Q12.a Q13.c
Detailed Solutions [Click Here]
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