Download App

Chemistry 2 Marks Questions

Electrochemistry · Bihar Board (BSEB) STD 12 Science (BSEB - English Medium). 70 questions.

Questions · Page 2 of 2

2 Marks Questions

Question 512 Marks
Define the following terms:
  1. Limiting molar conductivity.
  2. Fuel cell.
Answer
  1. The molar conductivity when concentration approaches to zero is called limiting molar conductivity.
  2. A fuel cell is a device which converts energy produced during the combustion of fuels like hydrogen, methane, methyl alcohol etc. directly into electrical energy. One such successful fuel cell is hydrogen-oxygen fuel cell.
View full question & answer→
Question 522 Marks
Tarnished silver contains $Ag_2S.$ Can this tarnish be removed by placing tarnished silver ware in an aluminium pan containing an inert electrolytic solution such as $NaCl?$ The standard electrode potential for half reaction:
$\text{Ag}_2\text{S(s) + 2e}^-\xrightarrow{\ \ \ \ \ \ \ }2\text{Ag(s) + S}^{2-}\text{is}-0.71\text{V}$
and for $\text{Al}^{3+}+3\text{e}^{-}\xrightarrow{ \ \ \ \ \ \ \ \ \ \ }2\text{Al(s) is}-1.66\text{V}$
Answer
${E^\circ}_{cell}$ for reaction of tarnished silver ware with aluminium pan is $(-0.71V) - (-1.66V)$
i.e., $+ 095V$
Tarnished silver ware, therefore, can be cleaned by placing it in an aluminium pan as ${E^\circ}_{cell}$ is positive.
View full question & answer→
MCQ 532 Marks
Note: In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: Mercury cell does not give steady potential.
Reason: In the cell reaction, ions are not involved in solution.
  • A
    Both assertion and reason are true and the reason is the correct explanation of assertion.
  • B
    Both assertion and reason are true and the reason is not the correct explanation of assertion.
  • C
    Assertion is true but the reason is false.
  • ✓
    Assertion is false but reason is true.
Answer
Correct option: D.
Assertion is false but reason is true.
Correct assertion is mercury cell gives steady potential.
View full question & answer→
MCQ 542 Marks
Note: In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: $E_{Cell}$ should have a positive value for the cell to function.
Reason: $\text{E}_{\text{cathode}}<\text{E}_{\text{anode}}$
  • A
    Both assertion and reason are true and the reason is the correct explanation of assertion.
  • B
    Both assertion and reason are true and the reason is not the correct explanation of assertion.
  • ✓
    Assertion is true but the reason is false.
  • D
    Both assertion and reason are false.
Answer
Correct option: C.
Assertion is true but the reason is false.
$\text{E}_{\text{Cell}}=\text{E}_{\text{cathode}}-\text{E}_{\text{anode}}$
To have positive value of $\text{E}_{\text{Cell}}=\text{E}_{\text{cathode}}<\text{E}_{\text{anode}}$
View full question & answer→
Question 552 Marks
Unlike dry cell, the mercury cell has a constant cell potential throughout its useful life. Why?
Answer
Electrolyte is not consumed in the cell process of mercury cell hence it will deliver the current at constant potential throughout its life.
View full question & answer→
Question 562 Marks
How will the $pH$ of brine $($aq. $NaCl$ solution$)$ be affected when it is electrolysed?
Answer
Aqueous solution of brine contains $Na+$, $CP,$ $H^+$ and $H^–.$ Electrode process are given as follows:
$2\text{H}^++2\text{e}^{-}\xrightarrow{\ \ \ \ \ \ \ \ \ \ \ \ }\text{H}_2\ \ \ \ (\text{cathode})$
$2\text{Cl}^-\xrightarrow{\ \ \ \ \ \ \ \ \ \ \ \ }\text{Cl}_2+2\text{e}\ \ \ \ (\text{Anode})$
Remaining solution will contain $NaOH,$ which is base, therefore, $pH$ will increase.
View full question & answer→
MCQ 572 Marks
Note: In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: For measuring resistance of an ionic solution an $AC$ source is used.
Reason: Concentration of ionic solution will change if $DC$ source is used.
  • ✓
    Both assertion and reason are true and the reason is the correct explanation of assertion.
  • B
    Both assertion and reason are true and the reason is not the correct explanation of assertion.
  • C
    Assertion is true but the reason is false.
  • D
    Both assertion and reason are false.
Answer
Correct option: A.
Both assertion and reason are true and the reason is the correct explanation of assertion.
$DC$ current can change the composition of electrolytic solution.
View full question & answer→
MCQ 582 Marks
Note: In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: Electrolysis of $NaCl$ solution gives chlorine at anode instead of $O_2$.
Reason: Formation of oxygen at anode requires overvoltage.
  • ✓
    Both assertion and reason are true and the reason is the correct explanation of assertion.
  • B
    Both assertion and reason are true and the reason is not the correct explanation of assertion.
  • C
    Assertion is true but the reason is false.
  • D
    Both assertion and reason are false.
Answer
Correct option: A.
Both assertion and reason are true and the reason is the correct explanation of assertion.

Formation of oxygen has lower value of $E^\circ$ than formation of chlorine even then it is not formed because it requires overvoltage.

View full question & answer→
MCQ 592 Marks
Note: In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: Copper sulphate can be stored in zinc vessel.
Reason: Zinc is less reactive than copper.
  • A
    Both assertion and reason are true and the reason is the correct explanation of assertion.
  • B
    Both assertion and reason are true and the reason is not the correct explanation of assertion.
  • C
    Assertion is true but the reason is false.
  • ✓
    Both assertion and reason are false.
     
Answer
Correct option: D.
Both assertion and reason are false.
 

Zinc will get dissolved in $CuSO_4$ solution since zinc is more reactive than copper.

View full question & answer→
Question 602 Marks
Under what condition is $\text{E}_{\text{Cell}}=0\text{ or }\Delta_\text{r}\text{G}=0?$
Answer
At equilibrium i.e., when the cell is completely discharged,
$\text{E}_{\text{Cell}}=0\text{ and }\Delta_\text{G}=0$
$\therefore\ \Delta_\text{G}=-\text{nFE}$
$\therefore\text{ when E}=0,\Delta_\text{G}$ is also equal zero.
View full question & answer→
MCQ 612 Marks
Note: In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: $Λ_m$ for weak electrolytes shows a sharp increase when the electrolytic solution is diluted.
Reason: For weak electrolytes degree of dissociation increases with dilution of solution.
  • ✓
    Both assertion and reason are true and the reason is the correct explanation of assertion.
  • B
    Both assertion and reason are true and the reason is not the correct explanation of assertion.
  • C
    Assertion is true but the reason is false.
  • D
    Both assertion and reason are false.
Answer
Correct option: A.
Both assertion and reason are true and the reason is the correct explanation of assertion.
Weak electrolytes dissociate partially in concentrated solution. On dilution, their degree of dissociation increases hence their Am increases sharply.
View full question & answer→
Question 622 Marks
A galvanic cell has electrical potential of 1.1V. If an opposing potential of 1.1V is applied to this cell, what will happen to the cell reaction and current flowing through the cell?
Answer
When the opposing potential becomes equal to electrical potential, the cell reaction stops and no current flows through the cell. Thus, there is no chemical reaction.
View full question & answer→
MCQ 632 Marks
Note: In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: Current stops flowing when $E_{Cell} = 0.$
Reason: Equilibrium of the cell reaction is attained.
  • ✓
    Both assertion and reason are true and the reason is the correct explanation of assertion.
  • B
    Both assertion and reason are true and the reason is not the correct explanation of assertion.
  • C
    Assertion is true but the reason is false.
  • D
    Both assertion and reason are false.
Answer
Correct option: A.
Both assertion and reason are true and the reason is the correct explanation of assertion.

At equilibrium $E_{Cell}= 0$ and therefore current stops flowing.

View full question & answer→
Question 642 Marks
What advantage do the fuel cells have over primary and secondary batteries?
Answer
Primary batteries contain a limited amount of reactants and are discharged when the reactants have been consumed. Secondary batteries can be recharged but take a long time to recharge. Fuel cell runs continuously as long as the reactants are supplied to it and products are removed continuously.
View full question & answer→
Question 652 Marks
State two advantages of $H_2-O_2$ fuel cell over ordinary cell.
Answer
  1. Advantages of fuel cell: a. It is a pollution-free device since no harmful products are formed.
  2. Its efficiency is about $75\%$ which is considerably higher than conventional cells.
  3. It is a continuous source of energy if the supply of gases is maintained.
View full question & answer→
Question 662 Marks
Solutions of two electrolytes $‘A’$ and $‘B’$ are diluted. The $Λ_m$ of $‘B’$ increases $1.5$ times while that of $A$ increases $25$ times. Which of the two is a strong electrolyte? Justify your answer.
Answer
Electrolyte $‘B’$ is strong as on dilution the number of ions remains the same, only interionic attraction decreases therefore increase in $∧_m$ is small.
View full question & answer→
Question 672 Marks
Why on dilution the m $Λ_m$ of $CH_3COOH$ increases drastically, while that of $CH_3COONa$ increases gradually?
Answer
In the case of $CH_3COOH,$ which is a weak electrolyte, the number of ions increase on dilution due to an increase in degree of dissociation.
$\text{CH}_3\text{COOH}+\text{H}_2\text{O}\rightleftharpoons\text{CH}_3\text{COO}^{-}(\text{aq}.)+\text{H}_3\text{O}^+$
In the case of strong electrolyte such as $CH_3COONa,$ the number of ions remains the same but the interionic attraction decreases.
View full question & answer→
Question 682 Marks
Silver is electrodeposited on a metallic vessel of total surface area $500\ cm^2$ by passing a current of 0.5 amp for two hours. Calculate the thickness of silver deposited.
$[$Given: Density of silver $= 10.5g\ cm^{-3},$ Atomic mass of silver $= 108$ amu, $F = 96,500\ C\ mol^{-1}]$
Answer
$\text{m}=\text{Z I t}=\frac{108}{96500}\times0.5\times2\times3600=4.029\text{g}$
$\text{d}=\frac{\text{m}}{\text{V}}\Rightarrow\text{V}=\frac{\text{m}}{\text{d}}$
$\text{V}=\frac{4.029}{10.5\text{g cm}^{-3}}=0.3837\text{cm}^3$
Let the thickness of silver deposited be $x\ cm.$
$\therefore\text{V = A}\times\text{x}$
$\text{x}=\frac{\text{V}}{\text{A}}$
$\text{x}=\frac{0.3837}{500}=7.67\times10^{-4}\text{cm}$
View full question & answer→
MCQ 692 Marks
Note: In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: Conductivity of all electrolytes decreases on dilution.
Reason: On dilution number of ions per unit volume decreases.
  • ✓
    Both assertion and reason are true and the reason is the correct explanation of assertion.
  • B
    Both assertion and reason are true and the reason is not the correct explanation of assertion.
  • C
    Assertion is true but the reason is false.
  • D
    Both assertion and reason are false.
Answer
Correct option: A.
Both assertion and reason are true and the reason is the correct explanation of assertion.
Conductivity always decreases with decrease in concentration both, for weak and strong electrolytes. This can be explained by the fact that the number of ions per unit volume that carry the current in a solution decreases on dilution.
View full question & answer→
Question 702 Marks
Write the cell reaction of a lead storage battery when it is discharged. How does the density of the electrolyte change when the battery is discharged?
Answer
$\text{Pb}+\text{PbO}_2+2\text{H}_2\text{SO}_4\xrightarrow{\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ }2\text{PbSO}_4+2\text{H}_2\text{O}$
Density of electrolyte decreases as water is formed and sulphuric acid is consumed as the product during discharge of the battery.
View full question & answer→
Generate Paper FreeAll Electrochemistry topics
2 Marks Questions - Page 2 - Chemistry STD 12 Science Questions - Vidyadip