All Practice Exams
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Chemistry
Electrochemistry
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1
The overall reaction taking place in mercury cell is:
A
ZnO(s) + Hg(l) → Zn(s) + HgO(s)
B
MgO(s) + Hg(l) → Mg(s) + HgO(s)
C
Mg(s) + HgO(s) → ZnO(s) + Hg(l)
D
Zn(Hg) + HgO(s) → ZnO(s) + Hg(l)
2
The product obtained at cathode during the electrolysis of dilute HCl is;
A
Cl2 (g)
B
H2 (g)
C
O2 (g)
D
N2 (g)
3
For a spontaneous cell reaction, the correct conditions are:
A
B
C
E°cell > 0 and ΔrG° > 0
D
4
If the molar conductivity of Mg2+ and Cl– at infinite dilution are respectively 106 S cm2 mol–1 and 76.3 S cm2 mol–1, then the limiting molar conductivity of MgCl2 is:
A
182.3 S cm2 mol–1
B
128.2 S cm2 mol–1
C
201.4 S cm2 mol–1
D
258.6 S cm2 mol–1
5
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R): Assertion (A): An electrolyte ‘A’ having specific conductance 2 × 10–6 ohm–1 cm–1 offers more resistance than an electrolyte ‘B’ having specific conductance 1 × 10–4 ohm–1 cm–1. Reason (R): Lesser the specific conductance, greater will be the resistance offered by an electrolyte. In the light of the above statements, choose the correct answer from the options given below:
A
A is true but R is false.
B
A is false but R is true.
C
Both A and R are true and R is the correct explanation of A.
D
Both A and R are true but R is NOT the correct explanation of A.
6
A
B
C
D
7
The expression connecting E°cell and Keq of the reaction occurring in a Galvanic cell is:
A
log Keq = nFE°/RT
B
log Keq = –nFE°/RT
C
ln Keq = nFE°/RT
D
–nFE°/RT = ln Keq
8
22 ohm and 0.022 ohm–1 cm–1 is the resistance and specific conductance respectively of a seminormal solution of sodium chloride. The value of the cell constant will be:
A
0.484 cm–1
B
0.926 cm–1
C
0.042 cm–1
D
0.123 cm–1
9
The molar conductance of NaCl, HCl and CH₃COONa at infinite dilution are 126.4, 425.90 and 91.0 S cm² mol⁻¹ respectively and at 25°C the molar conductance of 0.001 molar aqueous solution of CH₃COOH is 19 S cm² mol⁻¹. The percentage degree of ionization of CH₃COOH at the same concentration and temperature is
A
6.7%
B
5.8%
C
3.1%
D
4.9%
10
A
B
C
D
11
A
Both Statement I and Statement II are correct.
B
Statement I is correct but Statement II is incorrect.
C
Statement I is incorrect but Statement II is correct.
D
Both Statement I and Statement II are incorrect.
12
Standard electrode potential for Ni2+/Ni couple is –0.23V and that for the Zn2+/Zn couple is –0.76V. These two couples in their standard state are connected to make a cell. The cell potential will be:
A
+0.53 V
B
–0.53 V
C
+0.99 V
D
+2.0 V
13
A
40.800%
B
2.080%
C
20.800%
D
4.008%
14
A
37.18%
B
47%
C
48.78%
D
10.8%
15
A
B
C
D
16
A
22.4 L
B
44.8 L
C
5.6 L
D
11.2 L
17
The standard Gibbs free energy change of the reaction is: Cu2+(aq) + Sn(s) → Cu(s) + Sn2+(aq)
A
–31.86 kJ mol–1
B
–62.18 kJ mol–1
C
–79.29 kJ mol–1
D
–92.64 kJ mol–1
18
A
B
C
D
19
When a lead storage battery is charged, solid lead sulphate is converted into:
A
Pb(s) at cathode
B
PbO2(s) at cathode
C
PbO2(s) at anode
D
PbO(s) at anode
20
The gases obtained at cathode and anode during electrolysis of dil.H2SO4 respectively are:
A
O2 and H2
B
SO2 and H2
C
H2 and SO2
D
H2 and O2
21
The degree of dissociation (α) for 10–3 M acetic acid having molar conductivity 48.15 S cm2 mol–1 will be; (Given: Λ°m for acetic acid is 390.5 S cm2 mol–1)
A
0.012
B
0.123
C
0.256
D
0.341
22
The correct cell representation for the given cell reaction is: 2Cu(s) + 2Ag+(aq) → Cu2+(aq) + 2Ag(s)
A
Cu|Cu2+||Ag+|Ag
B
Ag|Ag+||Cu2+|Cu
C
Cu|Ag||Ag+|Cu2+
D
Cu2+|Cu||Ag|Ag+
23
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R): Assertion (A): Conductivity always decreases with decrease in concentration of both weak and strong electrolytes. Reason (R): The number of ions per unit volume that carry the current in a solution increases on dilution.
A
A is true but R is false.
B
A is false but R is true.
C
Both A and R are true and R is the correct explanation of A.
D
Both A and R are true but R is NOT the correct explanation of A.
24
The molar conductance’s of NaCl, HCl and CH3COONa at infinite dilution are 126.45, 426.16 and 91 ohm–1 cm2 mol–1 respectively. The molar conductance of CH3COOH at infinite dilution (Λ°m) is;
A
698.28 ohm–1 cm2 mol–1
B
540.48 ohm–1 cm2 mol–1
C
201.28 ohm–1 cm2 mol–1
D
390.71 ohm–1 cm2 mol–1
25
The correct relation between standard Gibbs energy and equilibrium constant is:
A
ΔrG° = –2.303RT ln K
B
ΔrG° = –RT ln K
C
ΔrG° = +2.303RT ln K
D
ΔrG° = +RT ln K
26
A
Ti
B
V
C
Cu
D
Cr
27
A
B
C
D
28
Which of the following is the weakest reducing agent?
A
Zn
B
Cu
C
H2
D
Li
29
Match List-I with List-II: List-I (Property) List-II (S.I Unit) (A) Conductance (B) Conductivity (C) Molar conductivity (D) Resistivity
A
A-II, B-III, C-IV, D-I
B
A-I, B-II, C-IV, D-III
C
A-III, B-IV, C-II, D-I
D
A-IV, B-I, C-III, D-II
30
Which of the following cell is also known as Leclanché cell?
A
Mercury cell
B
Dry cell
C
Nickel cadmium cell
D
Fuel cell
31
A
a(iv), b(ii), c(i), d(iii)
B
a(iii), b(i), c(ii), d(iv)
C
a(iii), b(iv), c(ii), d(i)
D
a(iv), b(iii), c(i), d(ii)
32
A standard hydrogen electrode has zero electrode potential because:
A
Hydrogen is easier to be oxidised
B
This electrode potential is assumed to be zero
C
Hydrogen atom has only one electron
D
Hydrogen is the lightest element
33
Given below are two statements: Statement I: Primary batteries, after the use over a period of time cannot be reused again. Statement II: A secondary cell after use can be recharged.
A
Both Statement I and Statement II are correct.
B
Statement I is correct but Statement II is incorrect.
C
Statement I is incorrect but Statement II is correct.
D
Both Statement I and Statement II are incorrect.
34
Which of the following statement is incorrect regarding H2–O2 fuel cells?
A
O2 is liberated at anode.
B
H2O is liberated at anode.
C
Overall reaction is: 2H2 + O2 → 2H2O
D
They are Galvanic cells.
35
1 gram equivalent substance is deposited when the electric current passed is equal to;
A
2F
B
3F
C
1F
D
0.1F
36
When the salt bridge is removed from cell, the cell voltage;
A
does not change
B
increases to maximum value
C
decreases to half the value
D
drops to zero
37
If the E°cell for the given cell reaction is 1.10 V, then the value of log Kc (where, Kc = equilibrium constant) is; Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s)
A
37.28
B
68.21
C
75.93
D
11.89
38
Which one of the following has the highest reduction potential?
A
Co3+
B
F2
C
O2
D
Li+
39
In Daniell cell, if the value of applied Eext (opposite potential) > 1.10 V, then which of the following statements is correct?
A
Electrons flow from Zn rod to Cu rod
B
Electrons flow from Cu rod to Zn rod
C
Zn dissolves at anode
D
Cu deposits at cathode
40
Dissociation constant (Ka) for acetic acid is given by:
A
(formula 1)
B
(formula 2)
C
(formula 3)
D
(formula 4)
41
During the electrolysis of molten sodium chloride, the time required to produce 35.5 g of chlorine gas using a current of 1930 amperes is;
A
55 sec
B
25 sec
C
50 sec
D
40 sec
42
Standard electrode potential of three metals A, B and C are –1.2 V, +0.2 V and –3.9 V respectively. The reducing power of these metals will be:
A
B > A > C
B
C > B > A
C
C > A > B
D
A > B > C
43
3 Faradays of electricity are passed through molten Al2O3, aqueous solution of CuSO4 and molten NaCl taken in three different electrolytic cells. The amount of Al, Cu and Na deposited at the cathodes will be in the ratio:
A
1 mole : 2 mole : 2 mole
B
1 mole : 1.5 mole : 3 mole
C
2 mole : 2 mole : 1 mole
D
1 mole : 1.5 mole : 2 mole
44
A
B
C
D
45
The product obtained at cathode during the electrolysis of aqueous solution of CuCl2 is:
A
Cu (s)
B
Cl2 (g)
C
O2 (g)
D
H2 (g)
46
Number of Faraday required to reduce 2 moles of MnO4− to Mn2+ is;
A
4 F
B
8 F
C
10 F
D
5 F
47
In which of the following half-reactions, reduction is taking place?
A
Fe2+ → Fe3+ + e–
B
Cu2+ + 2e− → Cu
C
2I– → I2 + 2e–
D
2H2O → O2 + 4H+ + 4e–
48
If the value of pH = 1 and pH2 = 1 atm, then the oxidation potential of hydrogen electrode is;
A
0.59 V
B
0.0295 V
C
0 V
D
0.059 V
49
A factory produces 40 kg of calcium in two hours by electrolysis. How much aluminium can be produced by same current in 2 hours?
A
22 kg
B
9 kg
C
18 kg
D
27 kg
50
Mark the correct choice of electrolytes represented in the graph:
A
A NH4OH, B NaCl
B
A NH4OH, B CH3COOH
C
A CH3COOH, B CH3COONa
D
A KCl, B CH3COOH
51
A
0.3
B
0.5
C
1.5
D
−0.5
52
Consider the following E°red values. Zn2+ + 2e– → Zn(s) ; E° = –0.76V Mg2+ + 2e– → Mg(s) ; E° = –2.36V Ca2+ + 2e– → Ca(s) ; E° = –2.87V Now, choose the correct statement.
A
Zn has the highest reducing power.
B
Mg has the lowest reducing power.
C
Ca has the highest reducing power.
D
Reducing power of Zn is more than Mg.
53
Match the List-I with List-II. List-I (Physical quantity) List-II (Formula) (A) G (B) G* (C) Λm (D) α
A
A-II, B-IV, C-I, D-III
B
A-I, B-III, C-II, D-IV
C
A-III, B-IV, C-II, D-I
D
A-IV, B-I, C-II, D-III
54
The number of Faraday required to reduce 5 moles of Cu2+ to Cu is:
A
10 F
B
2 F
C
5 F
D
4 F
55
The decreasing order of electrical conductivity of the following aqueous solution is I. 0.1 M HCl II. pure water III. 0.1 M CH3COOH
A
I > III > II
B
III > II > I
C
I > II > III
D
III > I > II
56
Given below are two statements: Statement I: Kohlrausch’s law states that the limiting molar conductivity of an electrolyte can be represented as the sum of the individual contributions of the anion and cation of the electrolyte. Statement II: Dry cell is commonly used in transistors and clocks.
A
Both Statement I and Statement II are correct.
B
Statement I is correct but Statement II is incorrect.
C
Statement I is incorrect but Statement II is correct.
D
Both Statement I and Statement II are incorrect.
57
For given cell; Zn|Zn+2(C1) || Zn+2(C2)|Zn; ΔG is negative if
A
C1 = C2
B
C1 > C2
C
C2 > C1
D
Can't be predicted
58
Limiting molar conductivity in water at 298 K is minimum for:
A
H+
B
Na+
C
K+
D
Ca2+