Electrochemistry Practice Questions - DPP for JEE

 Page 1


PART-I (Single Correct MCQs)
1. The mathematical expression for law of independent migration of ions
and Ostwald’s dilution law are given by
(a )
(b)
(c)
(d)
2. The equivalent conductance of  solution of a weak monobasic acid
is 8.0 mho cm
2
 and at infinite dilution is 400 mho cm
2
. The dissociation
constant of this acid is: (a) 1.25 × 10
–6
(b) 6.25 × 10
–4
(c) 1.25 × 10
–4
Page 2


PART-I (Single Correct MCQs)
1. The mathematical expression for law of independent migration of ions
and Ostwald’s dilution law are given by
(a )
(b)
(c)
(d)
2. The equivalent conductance of  solution of a weak monobasic acid
is 8.0 mho cm
2
 and at infinite dilution is 400 mho cm
2
. The dissociation
constant of this acid is: (a) 1.25 × 10
–6
(b) 6.25 × 10
–4
(c) 1.25 × 10
–4
(d) 1.25 × 10
–5
3. Molar ionic conductivities of a two-bivalent electrolytes x
2+
 and y
2–
 are
57 and 73 respectively. The molar conductivity of the solution formed
by them will be
(a) 130 S cm
2
 mol
–1
(b) 65 S cm
2
 mol
–1
(c) 260 S cm
2
 mol
–1
(d) 187 S cm
2
 mol
–1
4. If the E°
cell
 for a given reaction has a negative value, then which of the
following gives the correct relationships for the values of ?G° and K
eq
?
(a) ?G° > 0 ; K
eq
 > 1
(b) ?G° < 0 ; K
eq
 > 1
(c) ?G° < 0 ; K
eq
 < 1
(d) ?G° > 0 ; K
eq
 < 1
5. Standard electrode potentials are : Fe
+2
/Fe [ Eº = –0.44]; Fe
+3
/Fe
+2
  Eº =
+ 0.77 ; If Fe
+2
, Fe
+3
 and Fe blocks are kept together, then
(a) Fe
+3
 increases
(b) Fe
+3
 decreases
(c) remains unchanged
(d) Fe
+2
 decreases
6. An electrolytic cell contains a solution of Ag
2
SO
4
 and has platinum
electrodes. A current is passed until 1.6 gm of O
2
 has been liberated at
anode. The amount of silver deposited at cathode would be
(a) 107.88 g
(b) 1.6 g
(c) 0.8 g
(d) 21.60 g
7. For the cell reaction,
Page 3


PART-I (Single Correct MCQs)
1. The mathematical expression for law of independent migration of ions
and Ostwald’s dilution law are given by
(a )
(b)
(c)
(d)
2. The equivalent conductance of  solution of a weak monobasic acid
is 8.0 mho cm
2
 and at infinite dilution is 400 mho cm
2
. The dissociation
constant of this acid is: (a) 1.25 × 10
–6
(b) 6.25 × 10
–4
(c) 1.25 × 10
–4
(d) 1.25 × 10
–5
3. Molar ionic conductivities of a two-bivalent electrolytes x
2+
 and y
2–
 are
57 and 73 respectively. The molar conductivity of the solution formed
by them will be
(a) 130 S cm
2
 mol
–1
(b) 65 S cm
2
 mol
–1
(c) 260 S cm
2
 mol
–1
(d) 187 S cm
2
 mol
–1
4. If the E°
cell
 for a given reaction has a negative value, then which of the
following gives the correct relationships for the values of ?G° and K
eq
?
(a) ?G° > 0 ; K
eq
 > 1
(b) ?G° < 0 ; K
eq
 > 1
(c) ?G° < 0 ; K
eq
 < 1
(d) ?G° > 0 ; K
eq
 < 1
5. Standard electrode potentials are : Fe
+2
/Fe [ Eº = –0.44]; Fe
+3
/Fe
+2
  Eº =
+ 0.77 ; If Fe
+2
, Fe
+3
 and Fe blocks are kept together, then
(a) Fe
+3
 increases
(b) Fe
+3
 decreases
(c) remains unchanged
(d) Fe
+2
 decreases
6. An electrolytic cell contains a solution of Ag
2
SO
4
 and has platinum
electrodes. A current is passed until 1.6 gm of O
2
 has been liberated at
anode. The amount of silver deposited at cathode would be
(a) 107.88 g
(b) 1.6 g
(c) 0.8 g
(d) 21.60 g
7. For the cell reaction,
Cu
2+
 (C
1
, aq) + Zn(s) = Zn
2+
 (C
2
, aq) + Cu(s) of an electrochemical cell,
the change in free energy, ?G, at a given temperature is a function of
(a) ln (C
1
)
(b) ln (C
2
/C
1
)
(c) ln (C
2
)
(d) ln (C
1
 + C
2
)
8. The electrode potential  of a zinc electrode at 25°C with an
aqueous solution of 0.1 M ZnSO
4
 is [ = – 0.76 V. Assume 
 = 0.06 at 298 K].
(a) + 0.73
(b) – 0.79
(c) – 0.82
(d) – 0.70
9. A gas X at 1 atm is bubbled through a solution containing a mixture of
1 M Y
–
 and M Z
–
 at 25 °C. If the reduction potential of Z > Y > X, then,
(a) Y will oxidize X and not Z
(b) Y will oxidize Z and  not X
(c) Y will oxidize both X and Z
(d) Y will reduce both X and Z
10. For the electrochemical cell, 
= 0.44V and 
 
(X/X
–
) = 0.33V .
From this data one can deduce that
(a) M+X?M
+
+X
–
 is the spontaneous reaction
(b) M
+
+X
–
?M+X is the spontaneous reaction
(c) E
cell
 = 0.77 V
(d) E
cell
 = –0.77 V
11. Standard electrode potential data are useful for understanding the
Page 4


PART-I (Single Correct MCQs)
1. The mathematical expression for law of independent migration of ions
and Ostwald’s dilution law are given by
(a )
(b)
(c)
(d)
2. The equivalent conductance of  solution of a weak monobasic acid
is 8.0 mho cm
2
 and at infinite dilution is 400 mho cm
2
. The dissociation
constant of this acid is: (a) 1.25 × 10
–6
(b) 6.25 × 10
–4
(c) 1.25 × 10
–4
(d) 1.25 × 10
–5
3. Molar ionic conductivities of a two-bivalent electrolytes x
2+
 and y
2–
 are
57 and 73 respectively. The molar conductivity of the solution formed
by them will be
(a) 130 S cm
2
 mol
–1
(b) 65 S cm
2
 mol
–1
(c) 260 S cm
2
 mol
–1
(d) 187 S cm
2
 mol
–1
4. If the E°
cell
 for a given reaction has a negative value, then which of the
following gives the correct relationships for the values of ?G° and K
eq
?
(a) ?G° > 0 ; K
eq
 > 1
(b) ?G° < 0 ; K
eq
 > 1
(c) ?G° < 0 ; K
eq
 < 1
(d) ?G° > 0 ; K
eq
 < 1
5. Standard electrode potentials are : Fe
+2
/Fe [ Eº = –0.44]; Fe
+3
/Fe
+2
  Eº =
+ 0.77 ; If Fe
+2
, Fe
+3
 and Fe blocks are kept together, then
(a) Fe
+3
 increases
(b) Fe
+3
 decreases
(c) remains unchanged
(d) Fe
+2
 decreases
6. An electrolytic cell contains a solution of Ag
2
SO
4
 and has platinum
electrodes. A current is passed until 1.6 gm of O
2
 has been liberated at
anode. The amount of silver deposited at cathode would be
(a) 107.88 g
(b) 1.6 g
(c) 0.8 g
(d) 21.60 g
7. For the cell reaction,
Cu
2+
 (C
1
, aq) + Zn(s) = Zn
2+
 (C
2
, aq) + Cu(s) of an electrochemical cell,
the change in free energy, ?G, at a given temperature is a function of
(a) ln (C
1
)
(b) ln (C
2
/C
1
)
(c) ln (C
2
)
(d) ln (C
1
 + C
2
)
8. The electrode potential  of a zinc electrode at 25°C with an
aqueous solution of 0.1 M ZnSO
4
 is [ = – 0.76 V. Assume 
 = 0.06 at 298 K].
(a) + 0.73
(b) – 0.79
(c) – 0.82
(d) – 0.70
9. A gas X at 1 atm is bubbled through a solution containing a mixture of
1 M Y
–
 and M Z
–
 at 25 °C. If the reduction potential of Z > Y > X, then,
(a) Y will oxidize X and not Z
(b) Y will oxidize Z and  not X
(c) Y will oxidize both X and Z
(d) Y will reduce both X and Z
10. For the electrochemical cell, 
= 0.44V and 
 
(X/X
–
) = 0.33V .
From this data one can deduce that
(a) M+X?M
+
+X
–
 is the spontaneous reaction
(b) M
+
+X
–
?M+X is the spontaneous reaction
(c) E
cell
 = 0.77 V
(d) E
cell
 = –0.77 V
11. Standard electrode potential data are useful for understanding the
suitability of an oxidant in a redox titration. Some half cell reactions
and their standard potentials are given below:
  E° = 1.51 V
 E° = 1.38 V
E° = 0.77 V
E° = 1.40 V
Identify the only incorrect statement regarding the quantitative estimation of
aqueous Fe(NO
3
)
2
(a) can be used in aqueous HCl
(b) can be used in aqueous HCl
(c) can be used in aqueous H
2
SO
4
(d) can be used in aqueous H
2
SO
4
? 12. Conductance of 0.1 M KCl (conductivity = X ) filled in a
conductivity cell is Y . If the conductance of 0.1 M NaOH filled
in the same cell is Z , the molar conductance of NaOH will be
(a)
(b)
(c)
(d) 0.1
13. On the basis of the following E° values, the strongest oxidizing agent is
: 
Fe(CN)
6
]
4–
 ?[Fe(CN)
6
]
3–
 + e
– 
; E° = – 0.35 V
Fe
2+
 ? Fe
3+
 + e
–
;                            E° = – 0.77 V
(a) [Fe(CN)
6
]
4–
Page 5


PART-I (Single Correct MCQs)
1. The mathematical expression for law of independent migration of ions
and Ostwald’s dilution law are given by
(a )
(b)
(c)
(d)
2. The equivalent conductance of  solution of a weak monobasic acid
is 8.0 mho cm
2
 and at infinite dilution is 400 mho cm
2
. The dissociation
constant of this acid is: (a) 1.25 × 10
–6
(b) 6.25 × 10
–4
(c) 1.25 × 10
–4
(d) 1.25 × 10
–5
3. Molar ionic conductivities of a two-bivalent electrolytes x
2+
 and y
2–
 are
57 and 73 respectively. The molar conductivity of the solution formed
by them will be
(a) 130 S cm
2
 mol
–1
(b) 65 S cm
2
 mol
–1
(c) 260 S cm
2
 mol
–1
(d) 187 S cm
2
 mol
–1
4. If the E°
cell
 for a given reaction has a negative value, then which of the
following gives the correct relationships for the values of ?G° and K
eq
?
(a) ?G° > 0 ; K
eq
 > 1
(b) ?G° < 0 ; K
eq
 > 1
(c) ?G° < 0 ; K
eq
 < 1
(d) ?G° > 0 ; K
eq
 < 1
5. Standard electrode potentials are : Fe
+2
/Fe [ Eº = –0.44]; Fe
+3
/Fe
+2
  Eº =
+ 0.77 ; If Fe
+2
, Fe
+3
 and Fe blocks are kept together, then
(a) Fe
+3
 increases
(b) Fe
+3
 decreases
(c) remains unchanged
(d) Fe
+2
 decreases
6. An electrolytic cell contains a solution of Ag
2
SO
4
 and has platinum
electrodes. A current is passed until 1.6 gm of O
2
 has been liberated at
anode. The amount of silver deposited at cathode would be
(a) 107.88 g
(b) 1.6 g
(c) 0.8 g
(d) 21.60 g
7. For the cell reaction,
Cu
2+
 (C
1
, aq) + Zn(s) = Zn
2+
 (C
2
, aq) + Cu(s) of an electrochemical cell,
the change in free energy, ?G, at a given temperature is a function of
(a) ln (C
1
)
(b) ln (C
2
/C
1
)
(c) ln (C
2
)
(d) ln (C
1
 + C
2
)
8. The electrode potential  of a zinc electrode at 25°C with an
aqueous solution of 0.1 M ZnSO
4
 is [ = – 0.76 V. Assume 
 = 0.06 at 298 K].
(a) + 0.73
(b) – 0.79
(c) – 0.82
(d) – 0.70
9. A gas X at 1 atm is bubbled through a solution containing a mixture of
1 M Y
–
 and M Z
–
 at 25 °C. If the reduction potential of Z > Y > X, then,
(a) Y will oxidize X and not Z
(b) Y will oxidize Z and  not X
(c) Y will oxidize both X and Z
(d) Y will reduce both X and Z
10. For the electrochemical cell, 
= 0.44V and 
 
(X/X
–
) = 0.33V .
From this data one can deduce that
(a) M+X?M
+
+X
–
 is the spontaneous reaction
(b) M
+
+X
–
?M+X is the spontaneous reaction
(c) E
cell
 = 0.77 V
(d) E
cell
 = –0.77 V
11. Standard electrode potential data are useful for understanding the
suitability of an oxidant in a redox titration. Some half cell reactions
and their standard potentials are given below:
  E° = 1.51 V
 E° = 1.38 V
E° = 0.77 V
E° = 1.40 V
Identify the only incorrect statement regarding the quantitative estimation of
aqueous Fe(NO
3
)
2
(a) can be used in aqueous HCl
(b) can be used in aqueous HCl
(c) can be used in aqueous H
2
SO
4
(d) can be used in aqueous H
2
SO
4
? 12. Conductance of 0.1 M KCl (conductivity = X ) filled in a
conductivity cell is Y . If the conductance of 0.1 M NaOH filled
in the same cell is Z , the molar conductance of NaOH will be
(a)
(b)
(c)
(d) 0.1
13. On the basis of the following E° values, the strongest oxidizing agent is
: 
Fe(CN)
6
]
4–
 ?[Fe(CN)
6
]
3–
 + e
– 
; E° = – 0.35 V
Fe
2+
 ? Fe
3+
 + e
–
;                            E° = – 0.77 V
(a) [Fe(CN)
6
]
4–
(b) Fe
2+
(c) Fe
3+
(d) [Fe(CN)
6
]
3–
14. The variation of molar conductance of strong electrolyte with
(concentration)
½
 is represented by
(a)
(b)
(c)
(d)
15. A device that converts energy of combustion of fuels like hydrogen and
methane, directly into electrical energy is known as :
(a) Electrolytic cell
(b) Dynamo
(c) Ni-Cd cell
(d) Fuel cell
16. In acidic medium  is an oxidant as