UNIT#09 ELECTROCHEMISTRY Flashcards
The oxidation state of carbon atom in glucose is;
Zero
In which of the following substance does sulphur exhibit its highest oxidation state;
SO2Cl2
What is the oxidation state of oxygen is KO2:
-1/2
The apparent charge on an atom of an element in a molecule or ion is called oxidation number. It may be:
➡Positive
➡Negative
➡Zero or Fraction
The apparent charge on an atom in a molecule is:
Oxidation Number
The oxidation number of oxygen atoms in OF2 and H2O2:
➡+2
➡-1
The element on the reactant side which has been reduced is:
HI + H2SO4 ➡ I2 + SO2 + H2O
S
A redox reaction is:
MnO2 + 4H+ ➡ Mn+2 + 2H2O
2e are added on LHS
In which of the following changes there is a transfer of the five electrons:
MnO4-1 ➡ Mn+2
In the reaction H2S + Cl2 ➡2HCl + S, H2S acts as:
Reducing Agent
*H + MnO4 ➡ Mn+2 + 4H2O, which one is correct about the given equation:
5e in LHS
Which of the following reactions occur at the cathode:
Cu+2 + 2e ➡Cu
In which of the following changes there is a transfer of two electrons:
MnO4-2 ➡ MnO2
The reactions taking place at anode and cathode are respectively:
➡Oxidation
➡Reduction
The electrolysis product of molten NaCl at electrodes:
➡Na
➡Cl2
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
The cathodic reaction in the electrolysis of dilute H2SO4 with Pt electrodes;
Reduction
The product produced at the cathode when aqueous sodium chloride is electrolyzed:
H2
For the purification of copper, impure copper is made the _____
Anode
Cell potential depends upon:
➡Temeprature
➡Concentration of ions
➡Nature of electrolyte
When an element is in contact with 1M aqueous solution of its own ions, at 298K then the potential is called;
Standard Electrode Potential
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:
➡Electromotive Force
➡Cell Potential
Which is an incorrect statement about electrode potential?
➡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✅
Which is not true about SHE
➡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❌
The working condition/s for SHE
➡1 atm pressure
➡298K Temperature
➡1M H+ solution
The potential of SHE is taken as zero which is a ___ value
Arbitrary
The electrochemical series is based on:
Hydrogen Scale
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
If a salt bridge is removed from two half cells the emf is:
Dropped to zero
The cathode has the reduction potential:
More than anode
Al / Al+3 II Zn +2 / Zn galvanic cell, the anode is;
Al
Li has the least reduction potential in electrochemical series. Which has the highest?
F
The value of oxidation potential would be positive if it is;
Above SHE
In the oxidation number method, the final step to balance the equation is;
Inspection Method
Pure metal:
Does not corrode easily
H2 and O2 react in the presence of;
Pt
For a galvanic cell consisting of Zn and Fe dipped in their respective solutions:
Zn act as an anode
The least reactive transition metal;
Au
Elements like F2, and Cl2 lie:
Below Electrochemical series
Strongest reducing agent:
I-1
F2, Cl2, Br2 present in:
Below Electrochemical series
Which of the following is a potent reducing agent?
Li
In a galvanic cell, a salt bridge
An aqueous solution of KCl in gel
The efficiency of a fuel cell?
75%
Metals are ___?
Reducing Agents
Electrolysis of a dilute solution of NaCl results at the anode:
Oxygen
Each half-reaction in the ion-electron method is balanced by adding:
Both left and right-hand side
In metal hydrides the oxidation number of hydrogen is:
-1
The formation of ZnSO4 from blue copper sulphate solution is a spontaneous
Redox Reaction
Electrolysis is a:
Reduction Reaction
In balancing the redox equation the first thing is;
Write the skeleton equation
In electrochemical series reduction potential relates to only:
Standard Condition
In the ion-electron method, while balancing oxygen and Hydrogen atoms
First balance oxygen
The sulphate ion is:
Tetrahedral
Conversion of electrical energy into chemical energy is:
Electrochemistry
In Al2S3, the valency of Al is:
3
Which of the following is a feasible reaction?
Zn + HCl ➡ZnCl2 +H2
The element present at bottom of the electrochemical series acts as:
➡Cathode
➡Oxidizing Agent
The reaction which is responsible for the production of electricity in the voltaic cell is:
Redox
In all oxidation reactions, the atoms of an element in a chemical species lose electrons and increase their
Oxidation states
In MgCl2, the oxidation state of Cl is:
-1
Which one of the following behaves as a redox reaction?
2Na + Cl2 ➡2NaCl
In SO4 ^-2 the oxidation number of sulphur is:
+6
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
In NO3-¹, the oxidation number of N is:
+5
The oxidation state of carbon in C2O4-² is:
+3
The value of the oxidation number of chlorine in HClO3 is:
+5
In a voltaic cell, a salt bridge is used in order to:
Allow movement of ions between two cells
The potential difference of an electrochemical cell is measured in:
Voltmeter
In an electrochemical series, elements are arranged on the basis of:
Hydrogen Scale
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
The standard electrode potential of hydrogen is arbitrarily taken at 298K is:
0.00 Volt
Coinage metals Cu, Ag and Au are the least reactive because they have;
Positive Reduction Potential
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
Keeping in mind the electrode potential, which one o the following reaction is feasible?
Fe + CuSO4 ➡FeSO4 + Cu
Stronger is the oxidizing agent is the :
Reduction Potential
Which of the following metal does not liberate hydrogen on reaction with acid?
Pt
Which one of the following elements is the strongest reducing agent?
Sodium
Rusting of iron metal Fe occurs when Fe gets converted into Fe2O3. What happens with Fe?
Fe is oxidized
During space flights, astronauts obtained water from:
Fuel Cell
The electrolyte used in a fuel cell is;
KOH
In which of the following reactions does hydrogen acts as an oxidizing agent:
2Na + H2 ➡ 2NaH
Choose the true statement regarding the reaction given below:
2Na + Cl2 ➡2NaCl
Chlorine acts as an oxidizing agent and sodium as a reducing agent
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
Which of the following is the spontaneous reaction?
▶Zn + Cu+2 ➡ Zn+2 + Cu
(The electrode potential is Positive)
When a zinc electrode is coupled with a copper electrode in a galvanic cell?
Reduction takes place at the copper electrode
The oxidation state of nitrogen in NH4NO3 is:
-3 and 5
The oxidation state of “S” in the (S2O3)-2 is:
+2
The common oxidation number of halogens are;
-1
During the oxidation process, the oxidation number of an element;
Increases
The oxidation state of chlorine in ClF is:
+1
The oxidation number of “P” in PO4^-3
+5
To balance oxygen in ion electron method in acidic medium, we add:
H2O
In fuel cell, N2H4 reacts with N2H4 + O2 ➡N2 + 2H2O. The number of electrons lost by each nitrogen atom will be;
2
In the reaction
2Fe + 3Cl2 ➡2FeCl3
Fe is oxidized
Which is true about the reaction Mg + Cl2➡MgCl2
Mg is oxidized
Electrochemistry is concerned with the:
➡Nelson cell
➡Voltaic Cell
➡Hg-Cell
Which of the following has a non-spontaneous oxidation-reduction reaction?
Electrolytic Cell
The electrolytic products of which of the following are same as for the electrolysis of water.
Aqueous ZnSO4
Which of the following factors accounts for degree of dissociation of an electrolyte:
➡Nature of Electrolyte
➡Temperature
➡Concentration
List of elements based on hydrogen scale is called:
Electrochemical Series
The element that act as anode always have ____ position in electrochemical series:
Higher
For electrochemical cell Zn/ZnSO4 (1 M) || Fe2(SO4)3 (1M) /Fe, the number of electrons involved in balanced equation are;
6
The standard electrode potential is measured by:
Voltmeter
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
If Cu(NO302 is electrolyzed in presence of an inert electrode, product at cathode and at anode respectively:
➡Cu
➡O2
Metal that deposits at cathode when aqueous solution of its salt is electrolyzed:
Cu
Group 1 metals are -__ reactive than group 2 metals
More
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)
The oxidation no. of Cr is ____ in K2Cr2O7 or K2CrO4.
+6
In which of the following compound oxygen show -1 oxidation state:
Na2O2
The oxidation no. of Mn in [MnO4]-2 is:
+6
The oxidation numebr of oxygen atom in OF2 and H2O2:
+2, -1
How many electrons are required to balance the following half reaction:
2H2O + [MnO4]-1 ➡ MnO2 + [OH]-1
3e on left side
Which of the following is not a redox reaction?
BaCl2 + H2SO4 ➡BaSO4 +2HCl
During balancing of Redox equations by oxidation number method the ‘O’ and H atoms are balanced by:
Inspection Method
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
During the electrolysis of Brine solution, the gas liberated at the cathode is;
H2
The products of electrolysis of dilute aqueous sodium nitrate are:
➡H2
➡O2
The products of electrolysis will not be same in the case of:
CuSO4
Which of the following has a spontaneous oxidation-reduction reaction?
➡Galvanic Cell
➡Voltaic Cell
Standard electrode potential is measured at;
1 atm, 25°C, 1.0M
Electrode potential of an element can be calculated by comparing it with;
SHE
The standard reduction potential of Zn is;
-0.76
The conductivity of strong electrolyte:
Does no change considerably on dilution
Select the correct statement about salt bridge:
Maintain its neutrality
Standard electrode potential of a metal depends upon:
➡Temeprature
➡Molarity of the ions in solution
➡Nature of metal
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
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
Which reaction is not possible:
Zn + MgSO4 ➡ ZnSO4 + Mg
___ can displace hydrogen from acid more easily:
Ca
The +1 oxidation state of ‘P’ is found in:
H3PO2
The oxidation number of phosphorus in the compound s [PCl4]+ and [PCl6]- are respectively.
➡+5
➡+5
The value of the reduction potential of elements is independent upon:
Change in Pressure
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
SHE is used as a:
Reference Electrode
The reduction potential of aluminium is -1.66V. The oxidation potential of Al will be;
+1.66 V
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❌
The ability of elements to act as reducing agents ___ down to electrochemical series.
Decreases
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
The reaction taking place at the cathode is;
Reduction
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
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
The reduction potential of Cu= +0.34V and Zn=-0.76V. When these two are coupled the emf of cell is;
+1.10 V
Which of the following reaction is not feasible:
▶CuSO4 + Fe ➡❌
▶Mg + 2HCl ➡❌
▶MgSO4 + Zn ➡✅
▶2H2 + O2 ➡❌
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✅
The cell in which electrical energy is converted into chemical energy is;
Electrolytic Cell
On electrolysis of an aqueous solution of Na2SO4 using a graphite electrode, the product produced at anode is:
O2
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
Which one is an irreversible cell:
Dry cell
Which one of the following is the reduction reaction:
Br2 ➡2Br-
Which one of the following is not a constant quantity:
➡Single Electrode Potential✅
➡Standard Cell Potential❌
➡Standard Electrode Potential❌
➡Standard Reduction Potential❌
The electrode potential of standard hydrogen electrode is chosen as;
0 V
Which can replace hydrogen from dilute acids?
Zn
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
The difference in the electrolysis of concentrated and dilute NaCl is;
Product produced at the anode
Magnesium metal is extracted by the electrolysis of its:
Its fused chloride
Iron can be prevented from rusting by:
Connecting iron to more electropositive metal, a case of anodic protection
Standard hydrogen electrode has an arbitrarily fixed potential of;
0 V
The correct order of equivalent conductance at infinite dilution among LiCl, NaCl and KCl is;
KCl > NaCl > LiCl
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
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
If the sum of E values of the two half cells is negative, then;
The reaction will not be feasible
Which of the following cell can convert electrical energy directly into chemical energy?
Down’s cell
In a galvanic cell, the electrode occupies a lower position in the electrochemical series.
➡Will act as cathode
➡Reduction will take place on it
Greater the value of the standard reduction potential of the given species;
Greater is its tendency to accept electrons to undergo reduction
Coinage metals have the least reactivity because they have:
Positive Reduction Potentials
Which of the following is a secondary cell:
Ni-Cd cell
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
The oxidation potential of Mg and Al are +2.37V and 1.66V respectively. The Mg in a chemical reaction:
Will replace Al
Which can replace hydrogen from dilute acids?
Zn
The oxidation state of carbon-atom in glucose is:
Zero
The cell in which electrical energy is converted into chemical energy
Electrolytic Cell
The ability of elements to act as reducing agents ___ down to electrochemical series.
Decreases
If a strip of Cu-metal is placed in a solution of FeSO4 then:
No reaction occurs
“Al” metal is extracted from its ____ during electrolysis.
Oxides
Halogens are placed at a lower level of electrochemical series, this indicates that:
Halogens are good oxidizing agents but bad reducing agents
The electrolysis of product of molten NaCl electrodes:
➡Na
➡Cl2
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
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
Gold and Silver are least reactive due to;
Positive Reduction Potential
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
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❌
In reaction,
Zn + HNO3 ➡Zn(NO3)2 + NO + H2O.
Which is reduced?
“N” is reduced
The cell will function best if its calculated emf is:
Large +ve
Which one metal shows the maximum oxidation state?
Mn
NaCl is a strong electrolyte because:
It completely dissociates into ions at all concentration
If a salt bridge is removed from two half cells.
emf drop to zero
Fuel cells usually operate at;
High Temperature
The reduction potential of Cu = +0.34V and Zn = -0.76V. When these two are coupled the emf of the cell is;
+1.10V
Which is the correct statement or the element present at the top of the electrochemical series
It has a large positive reduction potential value
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.
The oxidation state of carbon in CNO-1 is;
+4
Which of the following cell can convert electrical energy directly into chemical energy;
Down’s Cell
The oxidation state of carbon-atom in glucose is;
Zero
The cell in which electrical energy is converted into chemical energy is:
Electrolytic cell
Which one metal shows maximum oxidation state;
Mn
Cell potential depends upon;
➡Temeparture
➡Nature of electrolyte
➡Concentration of ions
Which change in oxidation state takes place in nitrogen?
Cu + HNO3 ➡ Cu(NO3) + NO2 + H2O
+5 to +4
The element on the reactant side which has been reduced is:
HI + H2SO4 ➡I2 + SO2 + H2O
S
In reaction,
Zn + HNO3 ➡Zn(NO3)2 + NO + H2O
Which is reduced?
“N” is reduced
A redox reaction is;
MnO2 + 4H+ ➡Mn+2 + 2H2O
2e are added of LHS
Li has the least reduction potential in the electrochemical series. Which element has the highest E
F
The value of oxidation potential would be positive if it is;
Above SHE
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
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
In electrochemical series, metal will be easily oxidized if:
Reduction Potential Is Very Small
An element having E=-2.66 V. It is/ will be;
Easily oxidized
If E (cell) is positive, then the reaction will be:
Spontaneous
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
Standard hydrogen electrode has an arbitrary fixed potential o;
0 V
Fuel cells are mostly used in space air crafts as the source of:
➡Drinking Water
➡Power
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
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
If the sum of E values of the two half cells is negative, then;
The reaction will not be feasible
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
Greater the value of the standard reduction potential of the given species:
Greater is its tendency to accept electrons to undergo reduction
Coinage metals have the least reactivity because they have:
Positive Reduction Potentials
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
The oxidation potential of Mg and Al are +2.37V and 1.66V, respectively. The Mg in a chemical reaction:
Will replace Al
Which can replace hydrogen from dilute acids?
Pt
The ability of elements to act as reducing agent ___ down to electrochemical series
Decreases
If a strip of Cu-metal is placed in a solution of FeSO4 then:
No reaction occurs
Halogens are placed at a lower level of electrochemical series, this indicates that:
Halogens are good oxidizing agents but bad reducing agents
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
When an element is in contact with 1M aqueous solution of its own ions, at 298K then the potential is called;
Standard electrode Potential
Gold and silver are least reactive due to:
Positive Reduction Potential
Which of the following statement is correct?
Zn can replace Cu+2 in CuSO4
The cell will function best if its calculated emf is:
Large Positive
The reduction potential of Cu= +0.34V and Zn = -0.76V. When these two are coupled emf of the cell is;
+1.10 V
Magnesium metal is extracted by the electrolysis of its:
Its fused chloride
Iron can be prevented from rusting by:
Connecting iron to less electropositive metal, a case of cathodic protection
Which of the following statement is true about galvanic cells:
Reduction occurs at the cathode
The conduction of electricity through the solution is due to;
Movement of ions of the electrolyte
The electrolysis product of molten NaCl at electrodes:
➡Na
➡Cl2
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
NaCl is a strong electrolyte because:
It completely dissociates into ions at all concentrations
If a salt bridge is removed from two half cells
emf drop to zero
The value of the reduction potential of elements is dependent upon:
➡Change in temperature
➡Change in concentration
➡Change in pressure
Which of the following metal will liberate hydrogen gas when react with steam
Mg
In balancing redox reaction, the first thing is;
Write the skeleton equation
Each half reaction ion-electron method is balanced by adding:
e- either left or right hand size
In oxidation number method, the final step to balance equation is:
Inspection Method
2H+ and 2CrO4-2 ➡Cr2O7 + H2O
The charges are balanced in above equation by adding:
2e- on the right
In an operating electrochemical cell the function of a salt bridge is to;
Permit the migration of ions within the cell
Among the following molecules, in which does bromine show the lowest oxidation number:
HBr
In the reaction 4Fe + 3O2 ➡4Fe+2 + 6O-2. Which of the following statements is incorrect
Metallic iron is reduced to Fe+3
The heat contents o fall the elemetns in their standard states are taken to be;
Zero
One calorie is equal to;
4.184 J
In a reaction, the oxidation number of Cr decreases by 3. This indicates that Cr is;
Reduced
When a Zn piece is palced in CuSO4 solution, copper gets preciptated because:
Standard reduction potential of Zn is less than that of copper
During balancing of Redox equations by oxidation number method the ‘O2’ and H-atoms are balanced by:
Inspection Method
4OH- ➡O2 (9g) + 2H2O + xe
The ‘x’ electrons in above equation are:
4
If electricity is passed through CuSO4 solution by using Pt electrode, then which of the following possible change occurs:
Cu is deposited at anode
Stronger the oxidizing agent greater is the:
Reduction Potential
E (red) of an element can be calculated by comapring it with:
Standard Hydrogen Electrode
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
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
During following conversions ,the central atom in the product will have lower oxidation state than that of in reactant.
HNO3 ➡HNO2
Hydrogen gas is not liberated when the following metal is added to dil. HCl
Hg
The standard electrode potential is measured by:
Voltmeter
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
Which gas will be evolved at anode during electrolysis of aq. Na2SO4 solution:
O2
E of Fe+2/Fe is -0.44V; E of Cu+2/Cu is +0.34V. Then in the cell;
Cu+2 oxidizes Fe
Strong Reducing agents have high negative value of;
Reduction Potential
Zn + FeSO4➡ZnSO4 + Fe,
in the given reaction is:
Fe+2
What reaction will take place at SHE when Sn( E=-0.14V) half-cell is attached to it:
2H+ + 2e- ➡H2
Consider the following redox reaction:
2MnO4- + 3ClO3- + H2O ➡3ClO4- + 2MnO2 + 2OH-
The reducing agent is;
ClO3-
Identify the pair o species where nitrogen has same oxidation state in both species:
➡HNO3
➡N2O5
Which of the following has the lowest oxidation state of Mn?
MnSO4
Oxidation state of carbon in acetic acid is:
0
Which has no correspondence to the oxidation
Increase in ionic size
When MnO2 is reduced to Mn+2 then:
2e- are added on LHS
In which of hte following chagnes there is transfer of five electrons:
MnO4-1 ➡MnO2
In the reaction H2S + Cl2➡2HCl + S, S acts as;
Reducing agent
In which of the following substances, sulphur exhibits its highest oxidation state;
SO2
The electrochemical series is based on:
Hydrogen Scale
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
The ability of an element to act as oxidizing agent ___ down the electrochemical series
Increase
The strongest oxidizing agent among the Halogens is;
F2
Standard temperature for measurement of electrode potential is;
298K
Li has least reduction potential in electrochemical series. Which element has highest E (red)
F
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
The product is produced at the cathode when aqueous cupric chloride is electrolyzed;
Cu
Which one of the following is an oxidizing agent in the following reaction?
Zn + 2Ag+1 ➡Zn+2 +2Ag
Ag+1
In electrolytic solution, conduction is carried out by:
Ions
True about Zn-Cu cell:
E (cell) s 1.10
By electrolysis of brine solution, which of the following is deposited/released at the anode?
Cl2
Which of the following is reducing agent?
(COOH)2
Oxidaton number of nitrogen in NO3-1 is:
+5
Which of the following elements in glucose has zero oxidaton state?
C
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❌
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
In FeCl3 the oxidation state of Cl is;
-1
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✅
Which of the following is not conductor of electricity?
NaCl (s)
Li+ has a smaller ionic mobility than K+ because of the;
Greater degree of hydration of Li+
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❌
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
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
Na metal cannot be produced by electrolysis of aqueous
solution of NaCl.
Reduction of H2O is preferred to Na+
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)❌
In which one of the following reactions, hydrogen behaves as an oxidizing agent?
2Na + H2 ➡2NaH
When a dilute solution of salt is electrolyzed, a colourless gas is given off at the anode. Thegas is;
Oxygen
Coinage metals (Cu,Ag and Au) are the least reactive because they ahve:
Positive reduction Potential
All of the following are reducing agents EXCEPT:
CO2
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)✅
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❌
On the basis of knwoledge of electrochemical series, which reaction is not feasible:
Cu + H2SO4 ➡CuSO4 + H
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✅
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❌
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
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
In sodium suplhate (Na2SO4) what is the oxidation nmber of sulphur:
+6
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✅
To measure the standard electrode potential of Zinc, it is couple with;
SHE
Which one of the followign is not redox reactio?
MgO + 2HCl ➡MgCl2 + H2O
The elment which has greatest value of standard reduction potential (e) in the redox reacton acts as:
Strongest oxidizing agent
When a Zn strip is placed in CuSO4 solution, Cu gets
precipitated, because standard oxidation potential of
Zn is
> Cu
Which of the following has highest reduction potential?
Au
the reason which takes place at electrode when electricity is passed through the solution of an electrolyte is called:
Electrolysis
Strong reducing agents have large negativ value of ;
Reduction Potential
Which of hte followng is true in the case of Zn-Cu cell?
Zinc acts as an anode and copper as cathode
In a galvaic cell:
Chemcial energy is converted into electrical energy
Salt bridge transfers:
Ions
Temperature for the measruement of standard electrode potential is;
298K
The element that act as cathode always have ___ position i electrochemical series.
Lower
Consider the following redox reacton:
2MnO4- + 3ClO3- + H2O ➡3ClO4- + 2 MnO2 + 2OH-
The reducing agent is;
ClO3-1
Reference electrode of __- is used in the deetermination of electrode potential diferent elements:
Hydrogen
Zn + FeSO4 ➡ZnSO4 + Fe, in the given reactio nwhich fo the following is reduced
Fe+2
When fused PbBr 2 is electrolysed:
Pb deposited at cathode
Electrolysis is the process in which a chemical reaction takes palce at the expense o;
Electrical Energy
Which of the followign will form the cathode with respect to iron anode in an electrolyte?
Cu
Aqeuous solution of caustic soda on electroylsis produce ___ and __ at anode and cathode respectively
O2 and H2
Smaller is the value of standard reduction potential of substance
Greater is the reducing power of the substance
Which one of the following elements occurs only in one oxidation state?
Fluorine
Which of the following is a redox reaction?
Zn + 2HCl → ZnCl2 + H2
To balance oxygen in ion electron method in acidic medium, we add
H2O
Which statement below is NOT true for the reaction Fe+3 + e- ➡Fe+2
Fe +3 is oxidized
____ can displace Hydrogen from acid more easily
Ca
What reaction will take place at SHE. When Mg (E° = –2.37) half-cell is attached to it
2H+ + 2e ➡H2
Oxidation state of “P” in phosphonium ion (PH4+)is
-3
Arrange Mg, K and Na in the order of their decreasing reduction potentials
Mg,Na,K
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-
Which of the following metal can liberate hydrogen from halogen acid?
Zn
Which of the following element act as inert electrode?
Pt
Which one of the following metals will make a layer on other three metals when dipped in its aqueous solution?
Cu
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
Smaller is the value of standard reduction potential of substance
Greater is the reducing power of the substance
Whch element in the reaction below in oxidized?
2FeSO4 + Cl2 + H2SO4 ➡Fe2(SO4)3 + 2HCl
iron
What happens when a copper atom becomes a copper (II) ion?
It is oxidized by losing two electrons
In which pair the both the electropositive elements are possessing same oxidation state in both compounds:
Cu2Cl2 and NaCl
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
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
An electric current is passed through aqeous potassium sulphate K2SO4. What is formed and liberated at the cathode.
Hydrogen
Which statement about conduction of electricity is correct?
Electricity is conducted in an acid solution by ions
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
Electrochemistry is the branch of chemistry which deals with study of inter-conversion of:
Electrical Energy and Chemical Energy
Electrochemistry is the branch of chemistry which deals with study of inter-conversion of:
Electrical Energy and Chemical Energy
reactions in which oxidation state of at least any two of the reactants and products change are called ___ reactions.
Redox
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
The best reducing agent is;
I-1
