A compound which liberates reddish brown gas around the anode during electrolysis in its molten state is$-$
- ASodium chloride.
- BCopper $(II)$ oxide.
- CCopper $(II)$ sulphate.
- ✓Lead $(II)$ bromide.
Answer: D.
View full solution →Question types
Electrochemistry question types
397 questions across 7 question groups — pick any mix to generate a Chemistry paper with step-by-step answer keys.
397
Questions
7
Question groups
5
Question types
01
M.C.Q (1 Marks)
163 Q→02Assertion (A) & Reason (B) MCQ
18 Q→031 Marks Question
65 Q→042 Marks Questions
70 Q→053 Marks Question
60 Q→06Case study (4 Marks)
9 Q→075 Marks Questions
12 Q→Sample Questions
Electrochemistry questions
One sample from each question group in this chapter. Select any group above to see the full set with answer keys.
How much charge in Faraday is required for the reduction of $1$ mole of $Ag^+$ to $Ag?$
- A$19.29 \times 10^4C$
- ✓$96487C$
- C$38.59 \times 10^4C$
- D$4824C$
Answer: B.
View full solution →Negative terminal of a dry cell is formed by:
- ✓Zinc container.
- BCarbon rod.
- CGraphite rod.
- DBoth $A$ and $B.$
Answer: A.
View full solution →The process used to decompose compounds using electric current is called :
- ✓Electrolysis.
- BElectrification.
- CCurrents.
- DElectrolytic process.
Answer: A.
View full solution →Which of the following is not true?
- AThe electrode which pushes electrons into external circuit is known as anode
- BThe electrode which pulls electrons out of external circuit is known as cathode
- CWeak electrolytes conduct relatively small quantity of electricity than strong electrolytes
- ✓Effect of dilution on conductance of strong electrolyte can be explained by Arrhenius theory.
Answer: D.
View full solution →In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: The conductivity of solution is greater than pure solvent.
Reason: Conductivity depends upon number of the ions present in solution.
Assertion: The conductivity of solution is greater than pure solvent.
Reason: Conductivity depends upon number of the ions present in solution.
- ✓Assertion and reason both are correct statements and reason is correct explanation for assertion.
- BAssertion and reason both are correct statements but reason is not correct explanation for assertion.
- CAssertion is correct statement but reason is wrong statement.
- DAssertion is wrong statement but reason is correct statement.
Answer: A.
View full solution →In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion : On increasing dilution, the specific conductance keep on increasing.
Reason : On increasing dilution, degree of ionisation of weak electrolyte increases and molality of ions also
increases.
Assertion : On increasing dilution, the specific conductance keep on increasing.
Reason : On increasing dilution, degree of ionisation of weak electrolyte increases and molality of ions also
increases.
- AIf both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
- BIf both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
- CIf the Assertion is correct but Reason is incorrect.
- ✓If both the Assertion and Reason are incorrect.
Answer: D.
View full solution →In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: Conductance of a substance increases with decrease in resistance.
Reason: The inverse of resistance is called conductance.
Assertion: Conductance of a substance increases with decrease in resistance.
Reason: The inverse of resistance is called conductance.
- ✓Assertion and reason both are correct statements and reason is correct explanation for assertion.
- BAssertion and reason both are correct statements but reason is not correct explanation for assertion.
- CAssertion is correct statement but reason is wrong statement.
- DAssertion is wrong statement but reason is correct statement.
Answer: A.
View full solution →In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: The electrical resistance of any object decreases with increase in its length.
Reason: The electrical resistance of any object decreases with increase in its area of cross-section.
Assertion: The electrical resistance of any object decreases with increase in its length.
Reason: The electrical resistance of any object decreases with increase in its area of cross-section.
- AAssertion and reason both are correct statements and reason is correct explanation for assertion.
- BAssertion and reason both are correct statements but reason is not correct explanation for assertion.
- CAssertion is correct statement but reason is wrong statement.
- ✓Assertion is wrong statement but reason is correct statement.
Answer: D.
View full solution →In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: Zinc displaces copper from copper sulphate solution.
Reason: $E^\circ $ of zinc is $-0.76V$ and that of copper is $+0.34V.$
Assertion: Zinc displaces copper from copper sulphate solution.
Reason: $E^\circ $ of zinc is $-0.76V$ and that of copper is $+0.34V.$
- ✓Assertion and reason both are correct statements and reason is correct explanation for assertion.
- BAssertion and reason both are correct statements but reason is not correct explanation for assertion.
- CAssertion is correct statement but reason is wrong statement.
- DAssertion is wrong statement but reason is correct statement.
Answer: A.
View full solution →How much electricity in terms of Faraday is required to produce,
40.0g of Al from molten $Al_2O_3$.
View full solution →40.0g of Al from molten $Al_2O_3$.
How much electricity is required in coulomb for the oxidation of
1 mol of $\mathrm{H}_2 \mathrm{O}$ to $\mathrm{O}_2$.
View full solution →1 mol of $\mathrm{H}_2 \mathrm{O}$ to $\mathrm{O}_2$.
Can you store copper sulphate solutions in a zinc pot?
Consider the reaction:
$\mathrm{Cr}_2 \mathrm{O}_7^{2-}+14 \mathrm{H}^{+}+6 \mathrm{e}^{-} \rightarrow 2 \mathrm{Cr}^{3+}+8 \mathrm{H}_2 \mathrm{O}$
$\text { What is the quantity of electricity in coulombs needed to reduce } 1 \mathrm{~mol} \text { of } \mathrm{Cr}_2 \mathrm{O}_7 2^{-} \text {? }$
View full solution →$\mathrm{Cr}_2 \mathrm{O}_7^{2-}+14 \mathrm{H}^{+}+6 \mathrm{e}^{-} \rightarrow 2 \mathrm{Cr}^{3+}+8 \mathrm{H}_2 \mathrm{O}$
$\text { What is the quantity of electricity in coulombs needed to reduce } 1 \mathrm{~mol} \text { of } \mathrm{Cr}_2 \mathrm{O}_7 2^{-} \text {? }$
How much electricity is required in coulomb for the oxidation of
1 mol of FeO to $\mathrm{Fe}_2 \mathrm{O}_3$.
View full solution →1 mol of FeO to $\mathrm{Fe}_2 \mathrm{O}_3$.
Using the standard electrode potentials given in Table $3.1,$ predict if the reaction between the following is feasible:
$Fe^{3+} (aq)$ and $Br^– (aq)$
View full solution →$Fe^{3+} (aq)$ and $Br^– (aq)$
Using the standard electrode potentials given in Table $3.1,$ predict if the reaction between the following is feasible:
$Ag^+ (aq)$ and $Cu(s)$
View full solution →$Ag^+ (aq)$ and $Cu(s)$
Using the standard electrode potentials given in Table $3.1,$ predict if the reaction between the following is feasible:
$Br_2\ (aq)$ and $Fe^{2+}\ (aq).$
View full solution →$Br_2\ (aq)$ and $Fe^{2+}\ (aq).$
Write the chemistry of recharging the lead storage battery, highlighting all the materials that are involved during recharging.
Predict the products of electrolysis in each of the following:
An aqueous solution of $CuCl_2$ with platinum electrodes.
View full solution →An aqueous solution of $CuCl_2$ with platinum electrodes.
In the button cells widely used in watches and other devices the following reaction takes place:
$Zn(s) + Ag_2O(s) + H_2O(l) → Zn^{2+}(aq) + 2Ag(s) + 2OH^– (aq)$
Determine $\triangle_\text{r}\text{G}^\ominus$ and $\text{E}^\ominus$ for the reaction.
View full solution →$Zn(s) + Ag_2O(s) + H_2O(l) → Zn^{2+}(aq) + 2Ag(s) + 2OH^– (aq)$
Determine $\triangle_\text{r}\text{G}^\ominus$ and $\text{E}^\ominus$ for the reaction.
The cell in which the following reaction occurs:
$2\text{Fe}^{3+}(\text{aq})+2\text{I}^-(\text{aq})\rightarrow2\text{Fe}^{2+}(\text{aq})+\text{I}_2(\text{s})\ \text{has}\ \text{E}^\circ_{\text{cell}}$ = 0.236 V at 298 K. Calculate the standard Gibbs energy and the equilibrium constant of the cell reaction.
View full solution →$2\text{Fe}^{3+}(\text{aq})+2\text{I}^-(\text{aq})\rightarrow2\text{Fe}^{2+}(\text{aq})+\text{I}_2(\text{s})\ \text{has}\ \text{E}^\circ_{\text{cell}}$ = 0.236 V at 298 K. Calculate the standard Gibbs energy and the equilibrium constant of the cell reaction.
Conductivity of $0.00241 M$ acetic acid is $7.896 \times 10^{–5} S cm^{–1}$. Calculate its molar conductivity and if $\wedge^\circ_\text{m}$ for acetic acid is $390.5 S cm^2 mol^{–1}$, what is its dissociation constant?
View full solution →Three electrolytic cells A, B, C containing solutions of $ZnSO_4, AgNO_3$ and $CuSO_4$, respectively are connected in series. A steady current of $1.5$ amperes was passed through them until $1.45 g$ of silver deposited at the cathode of cell B. How long did the current flow? What mass of copper and zinc were deposited?
View full solution →Write the Nernst equation and emf of the following cells at $298\ K:$
$Pt(s) | Br_2(l) | Br^– (0.010 M) || H^+ (0.030 M) | H_2(g) (1 bar)|Pt(s).$
View full solution →$Pt(s) | Br_2(l) | Br^– (0.010 M) || H^+ (0.030 M) | H_2(g) (1 bar)|Pt(s).$
Standard electrode potentials are used for various processes:
$I_2 + 2e^- \rightarrow 2I^- ; E^\circ = 0.54 V$
$Cl_2 + 2e^- \rightarrow 2Cl^- ; E^\circ = 1.36 V$
$Mn^{3+} +e^- \rightarrow Mn^{2+}; E^\circ = 1.50 V$
$Fe^{3+} + e^- \rightarrow Fe^{2+}; E^\circ = 0.77 V$
$O_2 + 4H^+ + 4e^- \rightarrow 2H_2O ; E^\circ = 1.23 V$
The following questions are multiple choice questions. Choose the most appropriate answer:
View full solution →- It is used to measure relative strengths of various oxidants and reductants.
- It is used to calculate standard cell potential.
- It is used to predict possible reactions.
$I_2 + 2e^- \rightarrow 2I^- ; E^\circ = 0.54 V$
$Cl_2 + 2e^- \rightarrow 2Cl^- ; E^\circ = 1.36 V$
$Mn^{3+} +e^- \rightarrow Mn^{2+}; E^\circ = 1.50 V$
$Fe^{3+} + e^- \rightarrow Fe^{2+}; E^\circ = 0.77 V$
$O_2 + 4H^+ + 4e^- \rightarrow 2H_2O ; E^\circ = 1.23 V$
The following questions are multiple choice questions. Choose the most appropriate answer:
- Which of the following statements is correct?
- $Cl^-$ is oxidised by $O_2.$
- $Fe^{2+}$ is oxidised by iodine.
- $I^-$ is oxidised by chlorine.
- $Mn^{2+}$ is oxidised by chlorine.
- $Mn^{3+}$ is not stable in acidic medium, while $Fe^{3+}$ is stable because:
- $O_2$ oxidises $Mn^{2+}$ to $Mn^{3+}$
- $O_2$ oxidises both $Mn^{2+}$ to $Mn^{3+}$ and $Fe^{2+}$ to $Fe^{3+}$
- $Fe^{3+}$ oxidises $H_2O$ to $O_2$
- $Mn^{3+}$ oxidises $H_2O$ to $O_2$
- The strongest reducing agent in the aqueous solution is:
- $I^-$
- $Cl^-$
- $Mn^{2+}$
- $Fe^{2+}$
- The emf for the following reaction is:
- $-0.82\ V$
- $+0.82\ V$
- $-0.73\ V$
- $+0.73\ V$
- Which of the following statements is correct for the following reaction?
- The emf of the cell is positive.
- $Fe^{3+}$ oxidises $Mn^{2+}.$
- The reaction does not occur.
- All are correct.
Electrical work done in unit time is equal to electrical potential multiplied by total charge passed. ln order to obtain maximum work from a cell, the charge has to be passed reversibly. The reversible work done by a cell is equal to decrease in its Gibb's energy. Hence, Gibb's energy of reaction is given by
$\Delta\text{G}=\text{nFE}_\text{cell}$
Hence, Eis the emfof the cell and nFis the amount of energy.
In these questions (Q. No. i-Iv), a statement of assertion followed by a statement ofreason is given. Choose the correct answer out of the following choices.
View full solution →$\Delta\text{G}=\text{nFE}_\text{cell}$
Hence, Eis the emfof the cell and nFis the amount of energy.
In these questions (Q. No. i-Iv), a statement of assertion followed by a statement ofreason is given. Choose the correct answer out of the following choices.
- Assertion and reason both are correct statements and reason is correct explanation for assertion.
- Assertion and reason both are correct statements but reason is not correct explanation for assertion.
- Assertion is correct statement but reason is wrong statement.
- Assertion is wrong statement but reason is correct statement.
- Assertion: $\Delta\text{G}^\circ=-\text{nFE}^\circ$
- Assertion: An electrochemical cell can be set up only if the red ox reaction is spontaneous.
- Assertion: For an electrochemical cell, $\Delta\text{G}<0$ and $\text{E}_\text{cell}>0.$
- Assertion: Current stops flowing when $E_{cell} = 0.$
- Assertion: $E_{cell}$ should have a positive value for the cell to function.
All chemical reactions involve interaction of atoms and molecules. A large number of atoms/molecules are present in a few gram of any chemical compound varying with their atomic/ molecular masses. To handle such large number conveniently, the mole concept was introduced. All electrochemical cell reactions are also based on mole concept. For example, a $4.0$ molar aqueous solution of NaCl is prepared and 500mL of this solution is electrolysed. This leads to the evolution of chlorine gas at one of the electrode. The amount of products formed can be calculated by using mole concept.
The following questions are multiple choice questions. Choose the most appropriate answer:
View full solution →The following questions are multiple choice questions. Choose the most appropriate answer:
- The total number of moles of chlorine gas evolved is:
- $0.5$
- $1.0$
- $1.5$
- $1.9$
- If cathode is a Hg electrode, then the maximum weight of amalgam formed from this solution is:
- $300g$
- $446g$
- $396g$
- $296g$
- The total charge (coulomb) required for complete electrolysis is:
- $186000$
- $24125$
- $48296$
- $193000$
- In the electrolysis, the number of moles of electrons involved are:
- $2$
- $1$
- $3$
- $4$
- In electrolysis of aqueous $NaCl$ solution when Pt electrode is taken, then which gas is liberated at cathode?
- $H_2$gas
- $Cl_2$gas
- $O_2$gas
- None of these.
Two types of conductors are generally used, metallic and electrolytic. Free electrons are the current carrier in metallic and in electrolytic conductors, free ions. Specific conductance or conductivity of an electrolytic solution is given by
$\text{K}=\text{C}\times\frac{\text{l}}{\text{A}}$
where, $\text{C}\times\frac{1}{\text{R}}$ and $\frac{\text{l}}{\text{A}}=\text{G}^\star$ (cell constant)
Molar conductance $(\wedge_\text{m})$ and equivalent conductance $(\wedge_\text{e})$ of an electrolyte solution are calculated as
$\wedge_\text{m}=\frac{\text{K}\times1000}{\text{M}}$ or $\wedge_\text{e}=\frac{\text{K}\times1000}{\text{N}}$
where, M = molarity of solution and N is normality of solution. Molar conductance of strong electrolyte depends on the concentration.
$\wedge_\text{m}=\wedge^\circ_{\text{m}^-}\text{b}\sqrt{\text{C}}$
$\wedge^\circ_\text{m}=$ molar conductance at infinite dilution, b = constant, C = cone.of solution
In these questions (Q. No. i-iv), a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
View full solution →$\text{K}=\text{C}\times\frac{\text{l}}{\text{A}}$
where, $\text{C}\times\frac{1}{\text{R}}$ and $\frac{\text{l}}{\text{A}}=\text{G}^\star$ (cell constant)
Molar conductance $(\wedge_\text{m})$ and equivalent conductance $(\wedge_\text{e})$ of an electrolyte solution are calculated as
$\wedge_\text{m}=\frac{\text{K}\times1000}{\text{M}}$ or $\wedge_\text{e}=\frac{\text{K}\times1000}{\text{N}}$
where, M = molarity of solution and N is normality of solution. Molar conductance of strong electrolyte depends on the concentration.
$\wedge_\text{m}=\wedge^\circ_{\text{m}^-}\text{b}\sqrt{\text{C}}$
$\wedge^\circ_\text{m}=$ molar conductance at infinite dilution, b = constant, C = cone.of solution
In these questions (Q. No. i-iv), a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
- Assertion and reason both are correct statements and reason is correct explanation for assertion.
- Assertion and reason both are correct statements but reason is not correct explanation for assertion.
- Assertion is correct statement but reason is wrong statement.
- Assertion is wrong statement but reason is correct statement.
- Assertion: The molar conductivity of strong electrolyte decreases with increase in concentration.
- Assertion: The molar conductance of weak electrolyte at infinite dilution is equal to the sum of molar conductance of cations and anions.
- Assertion: Equivalent conductance of all electrolytes increases with increasing concentration.
- Assertion: Specific conductance decreases with dilution whereas equivalent conductance increases.
- Assertion: The ratio of specific conductivity to the observed conductance does not depend upon the concentration of the solution taken in the conductivity cell.
Molar conductivity of ions are given as product of charge on ions to their ionic mobilities and Faradays constant.
$\lambda_\text{A}\text{n}+=\text{n}\mu_\text{A}\text{n}+\text{F}$ (here $\mu$ is the ionic mobility of $A^{n+})$
For electrolytes say $A_xB_y,$ molar conductivity is given by
$\lambda_{\text{m}(\text{A}_\text{x}\text{B}_\text{y})}=\text{x}_\text{n}\mu_{\text{A}^\text{n}}+\text{F}+\text{y}_\text{m}\lambda_{\text{A}^\text{m}}-\text{F}$
The following questions are multiple choice questions. Choose the most appropriate answer:
View full solution →$\lambda_\text{A}\text{n}+=\text{n}\mu_\text{A}\text{n}+\text{F}$ (here $\mu$ is the ionic mobility of $A^{n+})$
For electrolytes say $A_xB_y,$ molar conductivity is given by
$\lambda_{\text{m}(\text{A}_\text{x}\text{B}_\text{y})}=\text{x}_\text{n}\mu_{\text{A}^\text{n}}+\text{F}+\text{y}_\text{m}\lambda_{\text{A}^\text{m}}-\text{F}$
|
Ions
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Ionic mobility
|
|
$K^+$
|
$7.616 \times 10^{-4}$
|
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$Ca^{2+}$
|
$12.33 \times 10^{-4}$
|
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$Br^-$
|
$8.09 \times 10^{-4}$
|
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$\text{SO}_{4}^{2-}$
|
$16.58 \times 10^{-4}$
|
- At infinite dilution, the equivalent conductance of $CaSO_4$ is:
- $256 \times 10^{-4}$
- $279$
- $23.7$
- $2.0 \times 10^{-8}$
- If the degree of dissociation of $CaSO_4$ solution is $10\%$ then equivalent conductance of $CaSO_4$ is:
- $3.59$
- $36.9$
- $27.9$
- $30.6$
- The correct order of equivalent conductance at infinite dilution of LiCl, NaCl, KCl is:
- $LiCl = NaCl = KCl$
- $LiCl > NaCl > KCl$
- $KCl > LiCl > NaCl$
- $KCl > NaCl > LiCl$
- What is the unit of equivalent conductivity?
- $ohm^{-1}\ cm^2\ eq^{-1}$
- $ohm\ cm^2\ eq-1$
- $ohm^{-1}\ cm\ eq^{-1}$
- $ohm\ cm^{-2}\ eq^{-2}$
- If the molar conductance value of $Ca^{2+}$ and $Cl^-$ at infinite dilution are $118.88 \times 10^{-4}m^2$ mho $mol^{-1}$ and $77.33 \times 10^{-4}m^2$ mho $mol^{-1}$ respectively then the molar conductance of $CaCl_2 ($in $m^2$ mho $mol^{-1})$ will be:
- $120.18 \times 10^{-4}$
- $135 \times 10^{-4}$
- $273.54 \times 10^{-4}$
- $192.1 \times 10^{-4}$
Match the terms given in Column I with the units given in Column II.
View full solution →|
|
Column I | Column II | |
| i. | $\text{K}$ | a. | $\text{I}\times\text{t}$ |
| ii. | $\wedge_{\text{m}}$ | b. | $\frac{\wedge_{\text{m}}}{\wedge^\circ_\text{m}}$ |
| iii. | $\alpha$ | c. | $\frac{\text{k}}{\text{c}}$ |
| iv. | $\text{Q}$ | d. | $\frac{\text{G}^*}{\text{R}}$ |
Match the terms given in Column I with the units given in Column II.
View full solution →|
|
Column I | Column II | |
| i. | $\wedge_{\text{m}}$ | a. | Intensive property. |
| ii. | $\text{E}^{\ominus}_{\text{Cell}}$ | b. | Depends on number of ions/volume. |
| iii. | $\text{K}$ | c. | Extensive property. |
| iv. | $\Delta_{\text{r}}\text{G}_{\text{Cell}}$ | d. | Increases with dilution. |
Consider the and answer the following questions.
i. Cell 'A' has $E_{\text {Cell }}=2 \mathrm{~V}$ and Cell 'B' has $E_{\text {Cell }}=1.1 \mathrm{~V}$ which of the two cells ' $A$ ' or ' $B$ ' will act as an electrolytic cell. Which electrode reactions will occur in this cell?
ii. If cell 'A' has $E_{C e l l}=0.5 \mathrm{~V}$ and cell 'B' has $E_{C e l l}=1.1 \mathrm{~V}$ then what will be the reactions at anode and cathode?
Match the items of Column I and Column II.
View full solution →|
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Column I
|
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Column II
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i.
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Lechlanche cell
|
a.
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Cell reaction $2H_2 + O_2 ⎯→ 2H_2O$
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|
ii.
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Ni–Cd cell
|
b.
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Does not involve any ion in solution and is used in hearing aids.
|
|
iii.
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Fuel cell
|
c.
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Rechargeable.
|
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iv.
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Mercury cell
|
d.
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Reaction at anode, $Zn ⎯→ Zn^{2+} + 2e^-$
|
|
|
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e.
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Converts energy of combustion into electrical energy.
|
Match the items of Column I and Column II.
View full solution →|
|
Column I
|
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Column II
|
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i.
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Lead storage battery
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a.
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Maximum efficiency.
|
|
ii.
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Mercury cell
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b.
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Prevented by galvanisation.
|
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iii.
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Fuel cell
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c.
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Gives steady potential.
|
|
iv.
|
Rusting
|
d.
|
Pb is anode, $PbO_2$ is cathode.
|
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