UNIT#09 ELECTROCHEMISTRY Flashcards
(362 cards)
1
Q
The oxidation state of carbon atom in glucose is;
A
Zero
2
Q
In which of the following substance does sulphur exhibit its highest oxidation state;
A
SO2Cl2
3
Q
What is the oxidation state of oxygen is KO2:
A
-1/2
4
Q
The apparent charge on an atom of an element in a molecule or ion is called oxidation number. It may be:
A
➡Positive
➡Negative
➡Zero or Fraction
5
Q
The apparent charge on an atom in a molecule is:
A
Oxidation Number
6
Q
The oxidation number of oxygen atoms in OF2 and H2O2:
A
➡+2
➡-1
7
Q
The element on the reactant side which has been reduced is:
HI + H2SO4 ➡ I2 + SO2 + H2O
A
S
8
Q
A redox reaction is:
MnO2 + 4H+ ➡ Mn+2 + 2H2O
A
2e are added on LHS
9
Q
In which of the following changes there is a transfer of the five electrons:
A
MnO4-1 ➡ Mn+2
10
Q
In the reaction H2S + Cl2 ➡2HCl + S, H2S acts as:
A
Reducing Agent
11
Q
*H + MnO4 ➡ Mn+2 + 4H2O, which one is correct about the given equation:
A
5e in LHS
12
Q
Which of the following reactions occur at the cathode:
A
Cu+2 + 2e ➡Cu
13
Q
In which of the following changes there is a transfer of two electrons:
A
MnO4-2 ➡ MnO2
14
Q
The reactions taking place at anode and cathode are respectively:
A
➡Oxidation
➡Reduction
15
Q
The electrolysis product of molten NaCl at electrodes:
A
➡Na
➡Cl2
16
Q
During the electrolysis of aqueous KNO3, H2 is produced at the cathode instead of potassium due to;
A
The reduction potential of potassium is less than hydrogen
17
Q
The cathodic reaction in the electrolysis of dilute H2SO4 with Pt electrodes;
A
Reduction
18
Q
The product produced at the cathode when aqueous sodium chloride is electrolyzed:
A
H2
19
Q
For the purification of copper, impure copper is made the _____
A
Anode
20
Q
Cell potential depends upon:
A
➡Temeprature
➡Concentration of ions
➡Nature of electrolyte
21
Q
When an element is in contact with 1M aqueous solution of its own ions, at 298K then the potential is called;
A
Standard Electrode Potential
22
Q
The electric current obtained from the galvanic cell is a result of electrons being pushed forced from the negative electrode, through an external wire, to the positive electrode. The force with which these electrons move through the wire is called:
A
➡Electromotive Force
➡Cell Potential
23
Q
Which is an incorrect statement about electrode potential?
A
➡It is the difference in potential of a cell, consisting of the particular electrode and the SHE❌
➡The potential set-up is when an electrode is in contact with one molar solution of its ions at standard conditions❌
➡The electrode potential of a single electrode can be measured directly✅
24
Q
Which is not true about SHE
A
➡Finely divided platinum black is used as an electrode❌
➡Temperature is kept at 25°C❌
➡One molar solution of H2SO4 is used as an electrolyte✅
➡Electrode potential of any element can be calculated by comparison method❌
25
The working condition/s for SHE
➡1 atm pressure
➡298K Temperature
➡1M H+ solution
26
The potential of SHE is taken as zero which is a ___ value
Arbitrary
27
The electrochemical series is based on:
Hydrogen Scale
28
SHE acts as an anode when connected with the Cu electrode but acts as a cathode with the Zn electrode which is correct
➡Zn has less reduction potential than hydrogen and Cu more
➡Zn has high oxidizing potential than hydrogen and Cu more
➡Zn is above in electrochemical series than hydrogen and Cu below
29
If a salt bridge is removed from two half cells the emf is:
Dropped to zero
30
The cathode has the reduction potential:
More than anode
31
Al / Al+3 II Zn +2 / Zn galvanic cell, the anode is;
Al
32
Li has the least reduction potential in electrochemical series. Which has the highest?
F
33
The value of oxidation potential would be positive if it is;
Above SHE
34
In the oxidation number method, the final step to balance the equation is;
Inspection Method
35
Pure metal:
Does not corrode easily
36
H2 and O2 react in the presence of;
Pt
37
For a galvanic cell consisting of Zn and Fe dipped in their respective solutions:
Zn act as an anode
38
The least reactive transition metal;
Au
39
Elements like F2, and Cl2 lie:
Below Electrochemical series
40
Strongest reducing agent:
I-1
41
F2, Cl2, Br2 present in:
Below Electrochemical series
42
Which of the following is a potent reducing agent?
Li
43
In a galvanic cell, a salt bridge
An aqueous solution of KCl in gel
44
The efficiency of a fuel cell?
75%
45
Metals are ___?
Reducing Agents
46
Electrolysis of a dilute solution of NaCl results at the anode:
Oxygen
47
Each half-reaction in the ion-electron method is balanced by adding:
Both left and right-hand side
48
In metal hydrides the oxidation number of hydrogen is:
-1
49
The formation of ZnSO4 from blue copper sulphate solution is a spontaneous
Redox Reaction
50
Electrolysis is a:
Reduction Reaction
51
In balancing the redox equation the first thing is;
Write the skeleton equation
52
In electrochemical series reduction potential relates to only:
Standard Condition
53
In the ion-electron method, while balancing oxygen and Hydrogen atoms
First balance oxygen
54
The sulphate ion is:
Tetrahedral
55
Conversion of electrical energy into chemical energy is:
Electrochemistry
56
In Al2S3, the valency of Al is:
3
57
Which of the following is a feasible reaction?
Zn + HCl ➡ZnCl2 +H2
58
The element present at bottom of the electrochemical series acts as:
➡Cathode
➡Oxidizing Agent
59
The reaction which is responsible for the production of electricity in the voltaic cell is:
Redox
60
In all oxidation reactions, the atoms of an element in a chemical species lose electrons and increase their
Oxidation states
61
In MgCl2, the oxidation state of Cl is:
-1
62
Which one of the following behaves as a redox reaction?
2Na + Cl2 ➡2NaCl
63
In SO4 ^-2 the oxidation number of sulphur is:
+6
64
Study the following redox reaction:
10Cl- + 16H+ + 2MnO4- ➡5Cl2 + 2Mn+2 + 8H2O
Which statement is true about this reaction?
Manganese is reduced from +7 to +2
65
In NO3-¹, the oxidation number of N is:
+5
66
The oxidation state of carbon in C2O4-² is:
+3
67
The value of the oxidation number of chlorine in HClO3 is:
+5
68
In a voltaic cell, a salt bridge is used in order to:
Allow movement of ions between two cells
69
The potential difference of an electrochemical cell is measured in:
Voltmeter
70
In an electrochemical series, elements are arranged on the basis of:
Hydrogen Scale
71
The E value of standard copper half-cell is +0.34V, measured when it is connected with SHE. In this case, the half-reaction taking place at SHE is:
H2 ➡ 2H+ + 2e
72
The standard electrode potential of hydrogen is arbitrarily taken at 298K is:
0.00 Volt
73
Coinage metals Cu, Ag and Au are the least reactive because they have;
Positive Reduction Potential
74
Study the following facts:
▶Zn ➡ Zn+2 + 2e E= +0.76 V
▶Cu ➡ Cu+2 +2e E= -0.34 V
Cu + Zn+2 ➡ Cu+2 + Zn
75
Keeping in mind the electrode potential, which one o the following reaction is feasible?
Fe + CuSO4 ➡FeSO4 + Cu
76
Stronger is the oxidizing agent is the :
Reduction Potential
77
Which of the following metal does not liberate hydrogen on reaction with acid?
Pt
78
Which one of the following elements is the strongest reducing agent?
Sodium
79
Rusting of iron metal Fe occurs when Fe gets converted into Fe2O3. What happens with Fe?
Fe is oxidized
80
During space flights, astronauts obtained water from:
Fuel Cell
81
The electrolyte used in a fuel cell is;
KOH
82
In which of the following reactions does hydrogen acts as an oxidizing agent:
2Na + H2 ➡ 2NaH
83
Choose the true statement regarding the reaction given below:
2Na + Cl2 ➡2NaCl
Chlorine acts as an oxidizing agent and sodium as a reducing agent
84
A cell is constructed of the following two half cells. What is the E+ of the cell?
Ag+ + e- ➡Ag Eo = +0.80V
Al+3 + e- ➡Al Eo = -1.67V
2.47 V
85
Which of the following is the spontaneous reaction?
▶Zn + Cu+2 ➡ Zn+2 + Cu
(The electrode potential is Positive)
86
When a zinc electrode is coupled with a copper electrode in a galvanic cell?
Reduction takes place at the copper electrode
87
The oxidation state of nitrogen in NH4NO3 is:
-3 and 5
88
The oxidation state of "S" in the (S2O3)-2 is:
+2
89
The common oxidation number of halogens are;
-1
90
During the oxidation process, the oxidation number of an element;
Increases
91
The oxidation state of chlorine in ClF is:
+1
92
The oxidation number of "P" in PO4^-3
+5
93
To balance oxygen in ion electron method in acidic medium, we add:
H2O
94
In fuel cell, N2H4 reacts with N2H4 + O2 ➡N2 + 2H2O. The number of electrons lost by each nitrogen atom will be;
2
95
In the reaction
2Fe + 3Cl2 ➡2FeCl3
Fe is oxidized
96
Which is true about the reaction Mg + Cl2➡MgCl2
Mg is oxidized
97
Electrochemistry is concerned with the:
➡Nelson cell
➡Voltaic Cell
➡Hg-Cell
98
Which of the following has a non-spontaneous oxidation-reduction reaction?
Electrolytic Cell
99
The electrolytic products of which of the following are same as for the electrolysis of water.
Aqueous ZnSO4
100
Which of the following factors accounts for degree of dissociation of an electrolyte:
➡Nature of Electrolyte
➡Temperature
➡Concentration
101
List of elements based on hydrogen scale is called:
Electrochemical Series
102
The element that act as anode always have ____ position in electrochemical series:
Higher
103
For electrochemical cell Zn/ZnSO4 (1 M) || Fe2(SO4)3 (1M) /Fe, the number of electrons involved in balanced equation are;
6
104
The standard electrode potential is measured by:
Voltmeter
105
Aluminium displaces hydrogen from dilute HCl whereas silver does not. The e.m.f of a cell prepared by combining Al /Al+3 and Ag/Ag+ is 2.46V. The reduction potential of silver electrode is +0.80V. The Eo (red) of aluminium electrode is:
-1.66 V
106
If Cu(NO302 is electrolyzed in presence of an inert electrode, product at cathode and at anode respectively:
➡Cu
➡O2
107
Metal that deposits at cathode when aqueous solution of its salt is electrolyzed:
Cu
108
Group 1 metals are -__ reactive than group 2 metals
More
109
If a strip of Cu metal is placed in a solution of FeSO4 then,
No reaction takes place
(reduction potential of Cu is higher than Fe)
110
The oxidation no. of Cr is ____ in K2Cr2O7 or K2CrO4.
+6
111
In which of the following compound oxygen show -1 oxidation state:
Na2O2
112
The oxidation no. of Mn in [MnO4]-2 is:
+6
113
The oxidation numebr of oxygen atom in OF2 and H2O2:
+2, -1
114
How many electrons are required to balance the following half reaction:
2H2O + [MnO4]-1 ➡ MnO2 + [OH]-1
3e on left side
115
Which of the following is not a redox reaction?
BaCl2 + H2SO4 ➡BaSO4 +2HCl
116
During balancing of Redox equations by oxidation number method the 'O' and H atoms are balanced by:
Inspection Method
117
In the electrolysis of dil. H2SO4 using platinum electrode, what is true:
Oxygen is evolved at anode
(At anode, [OH]-1 is oxidized to O2 due to higher oxidation potential to sulphate ions
118
During the electrolysis of Brine solution, the gas liberated at the cathode is;
H2
119
The products of electrolysis of dilute aqueous sodium nitrate are:
➡H2
➡O2
120
The products of electrolysis will not be same in the case of:
CuSO4
121
Which of the following has a spontaneous oxidation-reduction reaction?
➡Galvanic Cell
➡Voltaic Cell
122
Standard electrode potential is measured at;
1 atm, 25°C, 1.0M
123
Electrode potential of an element can be calculated by comparing it with;
SHE
124
The standard reduction potential of Zn is;
-0.76
125
The conductivity of strong electrolyte:
Does no change considerably on dilution
126
Select the correct statement about salt bridge:
Maintain its neutrality
127
Standard electrode potential of a metal depends upon:
➡Temeprature
➡Molarity of the ions in solution
➡Nature of metal
128
Which of the followign value of standard reduction potential suggest that the reducing power of an element is approximately equal o oxidizing power
0.00 V
129
If reduction potentials of different metals are:
A= -0.25V, B= -1.0V, C=-1.50V, D=-1.27V
Which can displace all others from their salts:
C
130
Which reaction is not possible:
Zn + MgSO4 ➡ ZnSO4 + Mg
131
___ can displace hydrogen from acid more easily:
Ca
132
The +1 oxidation state of 'P' is found in:
H3PO2
133
The oxidation number of phosphorus in the compound s [PCl4]+ and [PCl6]- are respectively.
➡+5
➡+5
134
The value of the reduction potential of elements is independent upon:
Change in Pressure
135
The potential is set up when an electrode is in contact with a molar solution of its own ion at 298K. This potential is represented as:
E^o
136
SHE is used as a:
Reference Electrode
137
The reduction potential of aluminium is -1.66V. The oxidation potential of Al will be;
+1.66 V
138
Which is an incorrect statement for the element present at the top of an electrochemical series.
➡It has a greater tendency to get oxidized❌
➡It can easily replace H2 from dilute acid❌
➡It has a large positive reduction potential value✅
➡It can reduce the metal lower in electrochemical series❌
139
The ability of elements to act as reducing agents ___ down to electrochemical series.
Decreases
140
For the cell, Cu+2 + Zn ➡Cu + Zn when
E(Zn) = +0.76V and E(Cu) = +0.34V, then cell voltage is
1.10 V
141
The reaction taking place at the cathode is;
Reduction
142
The two half cells of the galvanic cell are connected with each other through a salt bridge which:
Solutions in two half-cells electrically neutral
143
Given standard reduction potential for;
Fe+2 +2e- ➡Fe, (E=-0.440V)
Fe+3 + 3e- ➡Fe, (E=-0.036V)
The standard electrode potential for:
Fe+3 + e- ➡Fe+2 is:
0.404
144
The reduction potential of Cu= +0.34V and Zn=-0.76V. When these two are coupled the emf of cell is;
+1.10 V
145
Which of the following reaction is not feasible:
▶CuSO4 + Fe ➡❌
▶Mg + 2HCl ➡❌
▶MgSO4 + Zn ➡✅
▶2H2 + O2 ➡❌
146
Not correct about fuel cell:
➡Light and portable❌
➡Environmental Friendly❌
➡Hydrogen diffuses through porous chloride❌
➡Electrons flow through the external circuit from the anode to the cathode✅
147
The cell in which electrical energy is converted into chemical energy is;
Electrolytic Cell
148
On electrolysis of an aqueous solution of Na2SO4 using a graphite electrode, the product produced at anode is:
O2
149
When there is more than one anion present in the electrolyte, the order of increasing discharge ability is;
NO3- < Cl-1 < Br-1 < I-1 < OH-1
150
Which one is an irreversible cell:
Dry cell
151
Which one of the following is the reduction reaction:
Br2 ➡2Br-
152
Which one of the following is not a constant quantity:
➡Single Electrode Potential✅
➡Standard Cell Potential❌
➡Standard Electrode Potential❌
➡Standard Reduction Potential❌
153
The electrode potential of standard hydrogen electrode is chosen as;
0 V
154
Which can replace hydrogen from dilute acids?
Zn
155
The standard reduction potential values of three metallic cations X, Y and Z are 0.52, -3.03 and -1.18 respectively. The order of reducing the power of the corresponding metal is;
Y >Z >X
156
The difference in the electrolysis of concentrated and dilute NaCl is;
Product produced at the anode
157
Magnesium metal is extracted by the electrolysis of its:
Its fused chloride
158
Iron can be prevented from rusting by:
Connecting iron to more electropositive metal, a case of anodic protection
159
Standard hydrogen electrode has an arbitrarily fixed potential of;
0 V
160
The correct order of equivalent conductance at infinite dilution among LiCl, NaCl and KCl is;
KCl > NaCl > LiCl
161
The electrochemical series is useful in:
➡Prediction of the feasibility of a chemical reaction
➡Calculation of voltage
➡Comparison of the relative tendencies of the metals and non-metals to get oxidized or reduced
162
Normal aluminium electrode coupled with normal hydrogen electrode gives an emf of 1.66 volts and deflection of the needle toward Hydrogen. The standard electrode potential of aluminium is;
-1.66 V
163
If the sum of E values of the two half cells is negative, then;
The reaction will not be feasible
164
Which of the following cell can convert electrical energy directly into chemical energy?
Down's cell
165
In a galvanic cell, the electrode occupies a lower position in the electrochemical series.
➡Will act as cathode
➡Reduction will take place on it
166
Greater the value of the standard reduction potential of the given species;
Greater is its tendency to accept electrons to undergo reduction
167
Coinage metals have the least reactivity because they have:
Positive Reduction Potentials
168
Which of the following is a secondary cell:
Ni-Cd cell
169
Four metals A,B,C and D are having standard electrode potentials as -3.05, -1.66, -0.4, and 0.8 respectively. Which one will be the best reducing agent:
A
170
The oxidation potential of Mg and Al are +2.37V and 1.66V respectively. The Mg in a chemical reaction:
Will replace Al
171
Which can replace hydrogen from dilute acids?
Zn
172
The oxidation state of carbon-atom in glucose is:
Zero
173
The cell in which electrical energy is converted into chemical energy
Electrolytic Cell
174
The ability of elements to act as reducing agents ___ down to electrochemical series.
Decreases
175
If a strip of Cu-metal is placed in a solution of FeSO4 then:
No reaction occurs
176
"Al" metal is extracted from its ____ during electrolysis.
Oxides
177
Halogens are placed at a lower level of electrochemical series, this indicates that:
Halogens are good oxidizing agents but bad reducing agents
178
The electrolysis of product of molten NaCl electrodes:
➡Na
➡Cl2
179
SHE acts as an anode when connected with the Cu electrode but cathode with the Zn electrode because:
Zn has less reduction potential than hydrogen and Cu more
180
When an element is in contact with a 1M aqueous solution of its own ions, at 298K then the potential is called;
➡Standard Reduction Potential
➡Standard Electrode Potential
181
Gold and Silver are least reactive due to;
Positive Reduction Potential
182
During the electrolysis of aqueous KNO3, H2 is produced at the cathode instead of potassium due to;
The reduction Potential of potassium is less than hydrogen
183
Which of the following statement is correct;
➡Zn can replace Cu+2 in CuSO4✅
➡Cu can replace H+ in H2SO4❌
➡Cu can replace Zn+2 in ZnSO4❌
184
In reaction,
Zn + HNO3 ➡Zn(NO3)2 + NO + H2O.
Which is reduced?
"N" is reduced
185
The cell will function best if its calculated emf is:
Large +ve
186
Which one metal shows the maximum oxidation state?
Mn
187
NaCl is a strong electrolyte because:
It completely dissociates into ions at all concentration
188
If a salt bridge is removed from two half cells.
emf drop to zero
189
Fuel cells usually operate at;
High Temperature
190
The reduction potential of Cu = +0.34V and Zn = -0.76V. When these two are coupled the emf of the cell is;
+1.10V
191
Which is the correct statement or the element present at the top of the electrochemical series
It has a large positive reduction potential value
192
The two half cells of the galvanic cell are connected with each other through a salt bridge which:
Solutions in two half-cells electrically neutral.
193
The oxidation state of carbon in CNO-1 is;
+4
194
Which of the following cell can convert electrical energy directly into chemical energy;
Down's Cell
195
The oxidation state of carbon-atom in glucose is;
Zero
196
The cell in which electrical energy is converted into chemical energy is:
Electrolytic cell
197
Which one metal shows maximum oxidation state;
Mn
198
Cell potential depends upon;
➡Temeparture
➡Nature of electrolyte
➡Concentration of ions
199
Which change in oxidation state takes place in nitrogen?
Cu + HNO3 ➡ Cu(NO3) + NO2 + H2O
+5 to +4
200
The element on the reactant side which has been reduced is:
HI + H2SO4 ➡I2 + SO2 + H2O
S
201
In reaction,
Zn + HNO3 ➡Zn(NO3)2 + NO + H2O
Which is reduced?
"N" is reduced
202
A redox reaction is;
MnO2 + 4H+ ➡Mn+2 + 2H2O
2e are added of LHS
203
Li has the least reduction potential in the electrochemical series. Which element has the highest E
F
204
The value of oxidation potential would be positive if it is;
Above SHE
205
The standard reduction potential values of three metallic cations X, Y and Z are 0.52, -3.03 and -1.18 respectively. The order of reducing the power of the corresponding metal is;
Y > Z >X
206
E values of metals are W=-3.06 V, X= +2.07 V, Y=-1.85V, Z= +1.14V . Indicate the least reactive metal
X
207
In electrochemical series, metal will be easily oxidized if:
Reduction Potential Is Very Small
208
An element having E=-2.66 V. It is/ will be;
Easily oxidized
209
If E (cell) is positive, then the reaction will be:
Spontaneous
210
Zinc rod acts as the anode in Daniel cell but acts as a cathode when coupled with Al electrode, this is because E^o;
Zn > Al
211
Standard hydrogen electrode has an arbitrary fixed potential o;
0 V
212
Fuel cells are mostly used in space air crafts as the source of:
➡Drinking Water
➡Power
213
The electrochemical series is useful for:
➡Prediction of the feasibility of a chemical reaction
➡Calulation of voltage
➡Comparison of the relative tendencies of the metals and non-metals to get oxidized or reduced
214
Normal aluminium electrode coupled with normal hydrogen electrode gives an emf of 1.66 volts and deflection of the needle towards Hydrogen. The standard electrode potential of aluminium is;
-1.66 V
215
If the sum of E values of the two half cells is negative, then;
The reaction will not be feasible
216
In a galvanic cell, the electrode occupies a lower position in the electrochemical series.
➡Will act as a cathode
➡reduction will take place on it
217
Greater the value of the standard reduction potential of the given species:
Greater is its tendency to accept electrons to undergo reduction
218
Coinage metals have the least reactivity because they have:
Positive Reduction Potentials
219
Four metals A, B, C and D are having standard electrode potentials of -3.05, -1.66, -0.4 and 0.8 V respectively. Which one will be the best reducing agent?
A
220
The oxidation potential of Mg and Al are +2.37V and 1.66V, respectively. The Mg in a chemical reaction:
Will replace Al
221
Which can replace hydrogen from dilute acids?
Pt
222
The ability of elements to act as reducing agent ___ down to electrochemical series
Decreases
223
If a strip of Cu-metal is placed in a solution of FeSO4 then:
No reaction occurs
224
Halogens are placed at a lower level of electrochemical series, this indicates that:
Halogens are good oxidizing agents but bad reducing agents
225
SHE acts as an anode when connected with Cu electrode but cathode with Zn electrode because:
Zn has less reduction potential than hydrogen and Cu more
226
When an element is in contact with 1M aqueous solution of its own ions, at 298K then the potential is called;
Standard electrode Potential
227
Gold and silver are least reactive due to:
Positive Reduction Potential
228
Which of the following statement is correct?
Zn can replace Cu+2 in CuSO4
229
The cell will function best if its calculated emf is:
Large Positive
230
The reduction potential of Cu= +0.34V and Zn = -0.76V. When these two are coupled emf of the cell is;
+1.10 V
231
Magnesium metal is extracted by the electrolysis of its:
Its fused chloride
232
Iron can be prevented from rusting by:
Connecting iron to less electropositive metal, a case of cathodic protection
233
Which of the following statement is true about galvanic cells:
Reduction occurs at the cathode
234
The conduction of electricity through the solution is due to;
Movement of ions of the electrolyte
235
The electrolysis product of molten NaCl at electrodes:
➡Na
➡Cl2
236
During the electrolysis of aqueous KNO3, H2 is produced at the cathode instead of potassium due to;
The reduction potential of potassium is less than hydrogen
237
NaCl is a strong electrolyte because:
It completely dissociates into ions at all concentrations
238
If a salt bridge is removed from two half cells
emf drop to zero
239
The value of the reduction potential of elements is dependent upon:
➡Change in temperature
➡Change in concentration
➡Change in pressure
240
Which of the following metal will liberate hydrogen gas when react with steam
Mg
241
In balancing redox reaction, the first thing is;
Write the skeleton equation
242
Each half reaction ion-electron method is balanced by adding:
e- either left or right hand size
243
In oxidation number method, the final step to balance equation is:
Inspection Method
244
2H+ and 2CrO4-2 ➡Cr2O7 + H2O
The charges are balanced in above equation by adding:
2e- on the right
245
In an operating electrochemical cell the function of a salt bridge is to;
Permit the migration of ions within the cell
246
Among the following molecules, in which does bromine show the lowest oxidation number:
HBr
247
In the reaction 4Fe + 3O2 ➡4Fe+2 + 6O-2. Which of the following statements is incorrect
Metallic iron is reduced to Fe+3
248
The heat contents o fall the elemetns in their standard states are taken to be;
Zero
249
One calorie is equal to;
4.184 J
250
In a reaction, the oxidation number of Cr decreases by 3. This indicates that Cr is;
Reduced
251
When a Zn piece is palced in CuSO4 solution, copper gets preciptated because:
Standard reduction potential of Zn is less than that of copper
252
During balancing of Redox equations by oxidation number method the 'O2' and H-atoms are balanced by:
Inspection Method
253
4OH- ➡O2 (9g) + 2H2O + xe
The 'x' electrons in above equation are:
4
254
If electricity is passed through CuSO4 solution by using Pt electrode, then which of the following possible change occurs:
Cu is deposited at anode
255
Stronger the oxidizing agent greater is the:
Reduction Potential
256
E (red) of an element can be calculated by comapring it with:
Standard Hydrogen Electrode
257
Which of the following value of standard reduction potential suggest that the reducing power of an element is approximately equal to oxidizing power
0.00V
258
Standard reduction electrode potentials of three metals P,Q and R are +0.5V, -3.0V and -1.2V respectively. The order of reducing power of these emtals is;
Q > R > P
259
During following conversions ,the central atom in the product will have lower oxidation state than that of in reactant.
HNO3 ➡HNO2
260
Hydrogen gas is not liberated when the following metal is added to dil. HCl
Hg
261
The standard electrode potential is measured by:
Voltmeter
262
Aluminium displaces hydrogen from dilute HCl whereas silver does not.The e.m.f of a cell prepared by combining Al/Al+3 and Ag/Ag+ is 2.46V. The reduction potential of silver electrode is +0.80V. The E (red) of aluminium electrode is;
-1.66 V
263
Which gas will be evolved at anode during electrolysis of aq. Na2SO4 solution:
O2
264
E of Fe+2/Fe is -0.44V; E of Cu+2/Cu is +0.34V. Then in the cell;
Cu+2 oxidizes Fe
265
Strong Reducing agents have high negative value of;
Reduction Potential
266
Zn + FeSO4➡ZnSO4 + Fe,
in the given reaction is:
Fe+2
267
What reaction will take place at SHE when Sn( E=-0.14V) half-cell is attached to it:
2H+ + 2e- ➡H2
268
Consider the following redox reaction:
2MnO4- + 3ClO3- + H2O ➡3ClO4- + 2MnO2 + 2OH-
The reducing agent is;
ClO3-
269
Identify the pair o species where nitrogen has same oxidation state in both species:
➡HNO3
➡N2O5
270
Which of the following has the lowest oxidation state of Mn?
MnSO4
271
Oxidation state of carbon in acetic acid is:
0
272
Which has no correspondence to the oxidation
Increase in ionic size
273
When MnO2 is reduced to Mn+2 then:
2e- are added on LHS
274
In which of hte following chagnes there is transfer of five electrons:
MnO4-1 ➡MnO2
275
In the reaction H2S + Cl2➡2HCl + S, S acts as;
Reducing agent
276
In which of the following substances, sulphur exhibits its highest oxidation state;
SO2
277
The electrochemical series is based on:
Hydrogen Scale
278
Four metals W,X,Y, and Z havig standard electrode potentials as -3.05, -1.66,-0.4 and 0.8V respectively. Which one will be the best reducing agent;
W
279
The ability of an element to act as oxidizing agent ___ down the electrochemical series
Increase
280
The strongest oxidizing agent among the Halogens is;
F2
281
Standard temperature for measurement of electrode potential is;
298K
282
Li has least reduction potential in electrochemical series. Which element has highest E (red)
F
283
Two half-cell reactions are
2H+/H2 , E (red)=0.00V
Ag+1/Ag , E (red)=+0.80V
E (cell) of cell is;
+0.80V
284
The product is produced at the cathode when aqueous cupric chloride is electrolyzed;
Cu
285
Which one of the following is an oxidizing agent in the following reaction?
Zn + 2Ag+1 ➡Zn+2 +2Ag
Ag+1
286
In electrolytic solution, conduction is carried out by:
Ions
287
True about Zn-Cu cell:
E (cell) s 1.10
288
By electrolysis of brine solution, which of the following is deposited/released at the anode?
Cl2
289
Which of the following is reducing agent?
(COOH)2
290
Oxidaton number of nitrogen in NO3-1 is:
+5
291
Which of the following elements in glucose has zero oxidaton state?
C
292
All of the following statement about (oxidation) state is/are correct EXCEPT:
➡It is apparent charge on an atom in a compound✅
➡Its value is either zero, positive or negative✅
➡It can be variable✅
➡Xenon (Xe) can show maximum oxidation state +6 n its compounds❌
293
n the extraction of Al by electrolysis, why is it necessary to dissolve Al2O3 in molten cryolite?
To decrease high melting point of the electrolyte
294
In FeCl3 the oxidation state of Cl is;
-1
295
The process of decomposition of an electrolyte in solution or molten states by the passage of electric current is called electrolysis? All of the following statements about products as a result of electrolysis are correct EXCEPT:
➡They may be get deposited/released on the electrode surface❌
➡They may go out in the form of gases❌
➡Electrolytic material may get dissolved into the solution as ions❌
➡In Nelson cell, Na metal is a primary product✅
296
Which of the following is not conductor of electricity?
NaCl (s)
297
Li+ has a smaller ionic mobility than K+ because of the;
Greater degree of hydration of Li+
298
All of the following is/are characteristics properties of electrolytic cell EXCEPT:
➡It invoves conversion of electrical energy into chemical energy❌
➡In it anode has negative charge and cathode has positive charge✅
➡It is reverse of addition reaction❌
➡it is endothermic process❌
299
When there is more than one cations in the aqueous
solution of an electrolyte, the ions discharge at the
cathode can be predicted from the reactivity order of
elements given in the electrochemical series. Which of
the following is correct order of discharge of positive
ions at cathode?
Ag+ > Cu+2 > H+ > Pb+2
300
Which of the following is correct order of discharge of
negative ions on the anode electrode in case of
electrolysis of mixture of electrolytes?
I- > Br- > OH- > NO3-1
301
Na metal cannot be produced by electrolysis of aqueous
solution of NaCl.
Reduction of H2O is preferred to Na+
302
Which of the following is wrong about electrolysis?
➡Extraction of sodium by the elecrolysis of fused NaCl is carried in Down's cell❌
➡Ca and Mg metas are extracted by the electrolysis of their used chlorides❌
➡It is used for the extracton of blistered copper from electrolytic copper✅
➡Aluminium is extracted by electrolyzing fused bauxite
(Al2O3.2H2O) in the presence of fused cryolite
(Na3AlF6)❌
303
In which one of the following reactions, hydrogen behaves as an oxidizing agent?
2Na + H2 ➡2NaH
304
When a dilute solution of salt is electrolyzed, a colourless gas is given off at the anode. Thegas is;
Oxygen
305
Coinage metals (Cu,Ag and Au) are the least reactive because they ahve:
Positive reduction Potential
306
All of the following are reducing agents EXCEPT:
CO2
307
The potential set up when an electrode is in contact with
1M solution of its own ions at 298 K is known as
standard electrode potential (or standard reduction
potential denoted by E°). All of the following statements
about standard electrode potential are correct
EXCEPT:
➡Smaller is the E°red , greater is the reducing power of a
metal❌
➡E°red of Li+ is minimum (-3.04V)❌
➡Greater is the E°red , greater is the oxidizing power of a
non-metal ❌
➡E°red of Cl2 is maximum (+2.87V)✅
308
Identify incorrect statement about standard hydrogen electrode:
➡It is used as a reference electrode❌
➡Its E°red is zero or less than zero✅
➡When it is connected to zinc electrode in a galvanic cell,
it act as cathode❌
➡When it is connected to Cu electrode in a galvanic cell,
it act as anode❌
309
On the basis of knwoledge of electrochemical series, which reaction is not feasible:
Cu + H2SO4 ➡CuSO4 + H
310
When elements are arranged in the order of their
standard electrode potential on the basis of hydrogen
scale, the resulting list of elements is known as
Electrochemical series. Mark the incorrect statement
about electrochemical series:
➡Every top metal can displace lower one in redox reaction ❌
➡Every lower non-metal can displace higher one in redox
reaction❌
➡E (cell) = E (oxid) + E (red)❌
➡E (red) increases from bottom to top✅
311
Identify the incorrect statement:
➡Every top metal acts as anode❌
➡Every lower metal acts as cathode❌
➡Oxidizing power of an element decreases from top to bottom✅
➡Reducing power of an element decreases from top to bottom❌
312
On the electrolysis of aqueous solution of Na2SO4 by using inert electrode, which of the following is deposited/released on the cathode electrode?
H2 gas s released
313
On the electrolysis of H2SO4 (dil) solution by using inert electrode, which of the following is deposited or released at anode electrode
O2 gas is released
314
In sodium suplhate (Na2SO4) what is the oxidation nmber of sulphur:
+6
315
Salt bridge has all of the following functions EXCEPT:
➡It keeps separate both solutons❌
➡It maintains electrical neutrality in the cell❌
➡It maintains flow of electric crrent through external circuit❌
➡The positive charge around cathode electrode would prevent the electrons to flow from it✅
316
To measure the standard electrode potential of Zinc, it is couple with;
SHE
317
Which one of the followign is not redox reactio?
MgO + 2HCl ➡MgCl2 + H2O
318
The elment which has greatest value of standard reduction potential (e) in the redox reacton acts as:
Strongest oxidizing agent
319
When a Zn strip is placed in CuSO4 solution, Cu gets
precipitated, because standard oxidation potential of
Zn is
> Cu
320
Which of the following has highest reduction potential?
Au
321
the reason which takes place at electrode when electricity is passed through the solution of an electrolyte is called:
Electrolysis
322
Strong reducing agents have large negativ value of ;
Reduction Potential
323
Which of hte followng is true in the case of Zn-Cu cell?
Zinc acts as an anode and copper as cathode
324
In a galvaic cell:
Chemcial energy is converted into electrical energy
325
Salt bridge transfers:
Ions
326
Temperature for the measruement of standard electrode potential is;
298K
327
The element that act as cathode always have ___ position i electrochemical series.
Lower
328
Consider the following redox reacton:
2MnO4- + 3ClO3- + H2O ➡3ClO4- + 2 MnO2 + 2OH-
The reducing agent is;
ClO3-1
329
Reference electrode of __- is used in the deetermination of electrode potential diferent elements:
Hydrogen
330
Zn + FeSO4 ➡ZnSO4 + Fe, in the given reactio nwhich fo the following is reduced
Fe+2
331
When fused PbBr 2 is electrolysed:
Pb deposited at cathode
332
Electrolysis is the process in which a chemical reaction takes palce at the expense o;
Electrical Energy
333
Which of the followign will form the cathode with respect to iron anode in an electrolyte?
Cu
334
Aqeuous solution of caustic soda on electroylsis produce ___ and __ at anode and cathode respectively
O2 and H2
335
Smaller is the value of standard reduction potential of substance
Greater is the reducing power of the substance
336
Which one of the following elements occurs only in one oxidation state?
Fluorine
337
Which of the following is a redox reaction?
Zn + 2HCl → ZnCl2 + H2
338
To balance oxygen in ion electron method in acidic medium, we add
H2O
339
Which statement below is NOT true for the reaction Fe+3 + e- ➡Fe+2
Fe +3 is oxidized
340
____ can displace Hydrogen from acid more easily
Ca
341
What reaction will take place at SHE. When Mg (E° = –2.37) half-cell is attached to it
2H+ + 2e ➡H2
342
Oxidation state of “P” in phosphonium ion (PH4+)is
-3
343
Arrange Mg, K and Na in the order of their decreasing reduction potentials
Mg,Na,K
344
Which one of the following reactions takes place at the anode when an aqueous solution of CuSO4 is electrolyzed by using both copper electrodes?
Cu ➡Cu+2 +2e-
345
Which of the following metal can liberate hydrogen from halogen acid?
Zn
346
Which of the following element act as inert electrode?
Pt
347
Which one of the following metals will make a layer on other three metals when dipped in its aqueous solution?
Cu
348
he standard reduction potential of two electrodes are given as
A=+1.36V, B = -0.44 V the emf of the cell is
+1.80V
349
Smaller is the value of standard reduction potential of substance
Greater is the reducing power of the substance
350
Whch element in the reaction below in oxidized?
2FeSO4 + Cl2 + H2SO4 ➡Fe2(SO4)3 + 2HCl
iron
351
What happens when a copper atom becomes a copper (II) ion?
It is oxidized by losing two electrons
352
In which pair the both the electropositive elements are possessing same oxidation state in both compounds:
Cu2Cl2 and NaCl
353
Which change takes palce when aqeuous copper (II) sulphate is electrolyzed?
➡Copper is deposited at the negative electrode
➡Oxygen is evolved at the postive electrode
354
Chlorine is manufactured commercially by the electrolysis of aqeous sodum chloride (brine). Which other important products are made in this process?
Hydrogen and Sodium Hydroxide
355
An electric current is passed through aqeous potassium sulphate K2SO4. What is formed and liberated at the cathode.
Hydrogen
356
Which statement about conduction of electricity is correct?
Electricity is conducted in an acid solution by ions
357
Electrical energy is produced by a simple cell as a result of;
the transer of electrons from a more reactive to a less reactive element
358
Electrochemistry is the branch of chemistry which deals with study of inter-conversion of:
Electrical Energy and Chemical Energy
359
Electrochemistry is the branch of chemistry which deals with study of inter-conversion of:
Electrical Energy and Chemical Energy
360
reactions in which oxidation state of at least any two of the reactants and products change are called ___ reactions.
Redox
361
Which one of the following explains why a copper conducts electricty
The bonding electrons in the crystal lattice move when a potential diference is applied
362
The best reducing agent is;
I-1
