Chapter: Electrochemistry
Topic: Debye Huckel Limiting Law
Content: MCQ Questions & Solutions
Source: CSIR NET, GATE etc. Exams
Q1. For an aqueous solution at 25ºC, the Debye-Huckel
limiting law is given by
[NET June 2011]
(a) log γ+ = 0.509 | Z+ Z- | √µ
(b) log γ+ = 0.509 | Z+ Z- | µ
(c) log γ+ = -0.509 | Z+ Z- |
(d) log γ+ = -0.509 | Z+ Z- | µ2
Q2. Debye-Huckel
screening length (K-1) is a measure of size of diffuse ion cloud
around an ion, provided that
at 298 K, which of the following vales of K-1
is true for a 0.03 molal solution for Na2SO4 in water?
(εr = 100)
[NET June 2011]
(a) 10/9 nm
(b) 9/10 nm
(c) 10√2/9 nm
(d) 9/10√2 nm
Q3. For a
potentiometric titration, in the curve of emf (E) vs volume (V) of the titrant
added, the equivalence point is indicated by
[NET Dec 2011]
(a) |dE/dV|=0, |d2E/dV2|=0
(b) |dE/dV|=0, |d2E/dV2|>0
(c) |dE/dV|>0, |d2E/dV2|=0
(d) |dE/dV|>0, |d2E/dV2|>0
Q4. The
overall reaction for the passage of 1.0 faraday charge in the following cell is
given by ( t denotes the transport numbers )
Ag(s)-AgCl(s) |
KCl(a1) | KCL(a2) | AgCl(s)-Ag(s)
[NET Dec 2011]
(a) t+ KCl(a1) → t+ KCl(a2)
(b) t+ KCl(a2) → t+
KCl(a1)
(c) t- KCl(a1) → t-
KCl(a2)
(d) t- KCl(a2) → t-
KCl(a1)
Q5. The
spectrophotometric response for the titration of a mixture of Fe3+
and Cu2+ ions against EDTA is given below.
Given: Fe3+-EDTA
forms first (ε=0)
Cu2+-EDTA (ε≠0)
The correct
statement is:
[NET June 2012]
(a) volume ab = [Fe3+] and volume cd = [Cu2+]
(b) volume ab = [Cu2+] and volume cd = [Fe3+]
(c) volume ab = [Fe3+] and volume cd = excess EDTA
(d) volume ab = [Cu2+] and volume cd = excess EDTA
Q6. The
correct Nernst equation for the concentration cell:
Pt | H2(p)
| HCl(a+)1 | AgCl(s) | Ag - Ag | AgCl(s) | HCl(a+)2
| H2(p) | Pt
[NET June 2012]
Q7. On
subjecting 9.5 ml solution of Pb2+ of xM to polarographic
measurements, Id was found to be 1 µA. When 0.5 ml of 0.04 M Pb2+
solution was added before the measurement, the Id was found to be
1.25 µA. What should be the concentration x?
[NET Dec 2012]
(a) 0.0035
(b) 0.0400
(c) 0.0067
(d) 0.0080
Q8. In
complexometric titration
S (substrate) +
T (titrant) → P (product)
The end point is estimated
spectrophotometrically. If S and P have ε=0, the shape of titration curve would
look like
[NET June 2013]
Q9. Identify
from the following, the correct ionic strengths for
(A) 0.01 molal solution of NaCl and
(B) 0.01 molal Na2SO4 solution
[NET June 2013]
(a) (A) 0.010 mol kg-1 (B) 0.010 mol kg-1
(b) (A) 0.010 mol kg-1 (B) 0.030 mol kg-1
(c) (A) 0.010 mol kg-1 (B) 0.025 mol kg-1
(d) (A) 0.010 mol kg-1 (B) 0.015 mol kg-1
Q10. In
polarographic estimation, the limiting currents (µA) were
0.15, 4.65, 9.15, 27.15 when concentration (mM) of Pb(II) were 0, 0.5, 1.0, 3.0
respectively. An unknown Pb(II) gives a limiting current of 13.65 µA.
Concentration of Pb(II) in the unknown solution is:
[NET June 2014]
(a) 1.355 mM
(b) 1.408 mM
(c) 1.468 mM
(d) 1.500 mM
Answer Key
Q1.c Q2.a Q3.c Q4.a Q5.c Q6.c Q7.c Q8.c Q9.b Q10.d
Detailed Solutions [Click Here]
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