Quiz - chemistry - Electrochemistry-PYQ

Q1. The standard electrode potential ($E^circ$) values of $\text{Al}^{3+}/\text{Al}$, $\text{Ag}^{+}/\text{Ag}$, $\text{K}^{+}/\text{K}$ and $\text{Cr}^{3+}/\text{Cr}$ are $\mathbf{-1.66}$ V, $\mathbf{0.80}$ V, $\mathbf{-2.93}$ V and $\mathbf{-0.74}$ V, respectively. The correct decreasing order of reducing power of the metal is Source: orcusprep.in

NEET 2019

medium

Ag > Cr > Al > K

K > Al > Cr > Ag

K > Al > Ag > Cr

Al > K > Ag > Cr

Q2. A button cell used in watches function as following : $\text{Zn}(s) + \text{Ag}_2\text{O}(s) + \text{H}_2\text{O}(l) \rightleftharpoons 2\text{Ag}(s) + \text{Zn}^{2+}(\text{aq}) + 2\text{OH}^{-}(\text{aq})$. If half cell potentials are $\text{Zn}^{2+}(\text{aq}) + 2e^{-} \to \text{Zn}(s)$; $E^\circ = -0.76 \text{ V}$ and $\text{Ag}_2\text{O}(s) + \text{H}_2\text{O}(l) + 2e^{-} \to 2\text{Ag}(s) + 2\text{OH}^{-}(\text{aq})$; $E^\circ = 0.34 \text{ V}$. The cell potential will be Source: orcusprep.in

NEET 2013

easy

0.84 V

1.34 V

1.10 V

0.42 V

Q3. Standard reduction potentials of the half reactions are given below : $\text{F}_2(g) + 2e^{-} \to 2\text{F}^{-}(\text{aq})$; $E^\circ = +2.85 \text{ V}$; $\text{Cl}_2(g) + 2e^{-} \to 2\text{Cl}^{-}(\text{aq})$; $E^\circ = +1.36 \text{ V}$; $\text{Br}_2(l) + 2e^{-} \to 2\text{Br}^{-}(\text{aq})$; $E^\circ = +1.06 \text{ V}$; $\text{I}_2(s) + 2e^{-} \to 2\text{I}^{-}(\text{aq})$; $E^\circ = +0.53 \text{ V}$. The strongest oxidising and reducing agents respectively are Source: orcusprep.in

AIPMT Mains 2012

easy

$\text{F}_2$ and $\text{I}^{-}$

$\text{Br}_2$ and $\text{Cl}^{-}$

$\text{Cl}_2$ and $\text{Br}^{-}$

$\text{Cl}_2$ and $\text{I}_2$

Q4. Standard electrode potentials of three metals $\text{X}$, $\text{Y}$ and $\text{Z}$ are $\mathbf{-1.2 \text{ V}}$, $\mathbf{+0.5 \text{ V}}$ and $\mathbf{-3.0 \text{ V}}$ respectively. The reducing power of these metals will be Source: orcusprep.in

AIPMT 2011

easy

Y > Z > X

Y > X > Z

Z > X > Y

X > Y > Z

Q5. Standard electrode potential for $\text{Sn}^{4+}/\text{Sn}^{2+}$ couple is $\mathbf{+0.15 \text{ V}}$ and that for the $\text{Cr}^{3+}/\text{Cr}$ couple is $\mathbf{-0.74 \text{ V}}$. These two couples in their standard state are connected to make a cell. The cell potential will be Source: orcusprep.in

AIPMT 2011

easy

$+1.19 \text{ V}$

$+0.89 \text{ V}$

$+0.18 \text{ V}$

$+1.83 \text{ V}$

Q6. A solution contains $\text{Fe}^{2+}$, $\text{Fe}^{3+}$ and $\text{I}^{-}$ ions. This solution was treated with iodine at $35^\circ\text{C}$. $E^\circ$ for $\text{Fe}^{3+}/\text{Fe}^{2+}$ is $\mathbf{+0.77 \text{ V}}$ and $E^\circ$ for $\text{I}_2/2\text{I}^{-}$ is $\mathbf{0.536 \text{ V}}$. The favourable redox reaction is Source: orcusprep.in

AIPMT Mains 2011

medium

$\text{I}_2$ will be reduced to $\text{I}^{-}$

there will be no redox reaction

$\text{I}^{-}$ will be oxidised to $\text{I}_2$

$ ext{Fe}^{2+}$ will be oxidised to $\text{Fe}^{3+}$

Q7. Consider the following relations for $\text{EMF}$ of an electrochemical cell: $\text{(i) } \text{EMF of cell} = (\text{Oxidation potential of anode}) - (\text{Reduction potential of cathode})$; $\text{(ii) } \text{EMF of cell} = (\text{Oxidation potential of anode}) + (\text{Reduction potential of cathode})$; $\text{(iii) } \text{EMF of cell} = (\text{Reduction potential of cathode}) - (\text{Reduction potential of anode})$; $\text{(iv) } \text{EMF of cell} = (\text{Oxidation potential of anode}) - (\text{Oxidation potential of cathode})$. Which of the above relations are correct? Source: orcusprep.in

AIPMT Mains 2010

medium

(iii) and (i)

(i) and (ii)

(iii) and (iv)

(ii) and (iv)

Q8. On the basis of the following $E^\circ$ values, the strongest oxidizing agent is: $[\text{Fe}(\text{CN})_6]^{4-} \to [\text{Fe}(\text{CN})_6]^{3-} + e^{-}$; $E^\circ = -0.35 \text{ V}$ and $\text{Fe}^{2+} \to \text{Fe}^{3+} + e^{-}$; $E^\circ = -0.77 \text{ V}$ Source: orcusprep.in

AIPMT 2008

easy

$ ext{Fe}^{3+}$

$[\text{Fe}(\text{CN})_6]^{3-}$

$[\text{Fe}(\text{CN})_6]^{4-}$

$ ext{Fe}^{2+}$

Q9. A hypothetical electrochemical cell is shown below : $\text{A}/\text{A}^{+}(\text{x M}) || \text{B}^{+}(\text{y M})/\text{B}$. The emf measured is $+ 0.20 \text{ V}$. The cell reaction is Source: orcusprep.in

AIPMT 2006

hard

$\text{A} + \text{B}^{+} \to \text{A}^{+} + \text{B}$

$\text{A}^{+} + \text{B} \to \text{A} + \text{B}^{+}$

$\text{A}^{+} + e^{-} \to \text{A}$; $\text{B}^{+} + e^{-} \to \text{B}$

the cell reaction cannot be predicted.

Q10. $E^\circ_{\text{Fe}^{2+}/\text{Fe}} = -0.441 \text{ V}$ and $E^\circ_{\text{Fe}^{3+}/\text{Fe}^{2+}} = 0.771 \text{ V}$, the standard $\text{EMF}$ of the reaction $\text{Fe} + 2\text{Fe}^{3+} \to 3\text{Fe}^{2+}$ will be Source: orcusprep.in

AIPMT 2006

medium

0.111 V

0.330 V

1.653 V

1.212 V

Q11. Standard electrode potentials are $\text{Fe}^{2+}/\text{Fe}$; $E^\circ = -0.44 \text{ V}$ and $\text{Fe}^{3+}/\text{Fe}^{2+}$; $E^\circ = 0.77 \text{ V}$. $\text{Fe}^{2+}$, $\text{Fe}^{3+}$ and $\text{Fe}$ blocks are kept together, then Source: orcusprep.in

AIPMT 2001

medium

$\text{Fe}^{3+}$ increases

$\text{Fe}^{3+}$ decreases

$\text{Fe}^{2+}/\text{Fe}^{3+}$ remains unchanged

$\text{Fe}^{2+}$ decreases.

Q12. Electrode potential for the following half-cell reactions are $\text{Zn} \to \text{Zn}^{2+} + 2e^{-}$; $E^\circ = + 0.76 \text{ V}$; $\text{Fe} \to \text{Fe}^{2+} + 2e^{-}$; $E^\circ = + 0.44 \text{ V}$. The $\text{EMF}$ for the cell reaction $\text{Fe}^{2+} + \text{Zn} \to \text{Zn}^{2+} + \text{Fe}$ will be Source: orcusprep.in

AIPMT 1996

easy

$- 0.32 \text{ V}$

$+ 1.20 \text{ V}$

$- 1.20 \text{ V}$

$+ 0.32 \text{ V}$

Q13. An electrochemical cell is set up as : $\text{Pt}; \text{H}_2 (1 \text{ atm})|\text{HCl}(0.1 \text{ M}) || \text{CH}_3\text{COOH} (0.1 \text{ M}) |\text{H}_2 (1 \text{ atm}); \text{Pt}$. The $\text{e.m.f.}$ of this cell will not be zero, because Source: orcusprep.in

AIPMT 1995

medium

acids used in two compartments are different

e.m.f. depends on molarities of acids used

the temperature is constant

$\text{pH}$ of $0.1 \text{ M} \text{ HCl}$ and $0.1 \text{ M} \text{ CH}_3\text{COOH}$ is not same.

Q14. Standard reduction potentials at $25^\circ\text{C}$ of $\text{Li}^{+}/\text{Li}$, $\text{Ba}^{2+}/\text{Ba}$, $\text{Na}^{+}/\text{Na}$ and $\text{Mg}^{2+}/\text{Mg}$ are $\mathbf{-3.05}$, $\mathbf{-2.90}$, $\mathbf{-2.71}$ and $\mathbf{-2.37 \text{ volt}}$ respectively. Which one of the following is the strongest oxidising agent? Source: orcusprep.in

AIPMT 1994

easy

$\text{Ba}^{2+}$

$\text{Mg}^{2+}$

$\text{Na}^{+}$

$\text{Li}^{+}$

Q15. A solution of potassium bromide is treated with each of the following. Which one would liberate bromine? Source: orcusprep.in

AIPMT 1993

medium

Hydrogen iodide

Sulphur dioxide

Chlorine

Iodine

Q16. For the cell reaction : $2\text{Fe}^{3+}(\text{aq}) + 2\text{I}^{-}(\text{aq}) \rightleftharpoons 2\text{Fe}^{2+}(\text{aq}) + \text{I}_2(\text{aq})$, $E^\circ_{\text{cell}} = 0.24 \text{ V}$ at $298 \text{ K}$. The standard Gibbs’ energy ($\Delta_{\text{r}}G^\circ$)of the cell reaction is $\text{ (Given } F = 96500 \text{ C mol}^{-1})$ Source: orcusprep.in

NEET 2019

easy

23.16 kJ mol$^{-1}$

$-46.32 \text{ kJ mol}^{-1}$

$-23.16 \text{ kJ mol}^{-1}$

46.32 kJ mol$^{-1}$

Q17. For a cell involving one electron, $E^\circ_{\text{cell}} = 0.59 \text{ V}$ at $298 \text{ K}$, the equilibrium constant for the cell reaction is $\text{ (Given } \frac{2.303 RT}{F} = 0.059 \text{ V } \text{ at } T = 298 \text{ K)}$ Source: orcusprep.in

NEET 2019

easy

$1.0 \times 10^{30}$

$1.0 \times 10^{2}$

$1.0 \times 10^{5}$

$1.0 \times 10^{10}$

Q18. In the electrochemical cell : $\text{Zn}|\text{ZnSO}_4(0.01 \text{ M})||\text{CuSO}_4(1.0 \text{ M})|\text{Cu}$, the $\text{emf}$ of this Daniell cell is $E_1$. When the concentration of $\text{ZnSO}_4$ is changed to $1.0 \text{ M}$ and that of $\text{CuSO}_4$ changed to $0.01 \text{ M}$, the $\text{emf}$ changes to $E_2$. From the followings, which one is the relationship between $E_1$ and $E_2$? $\text{ (Given, } \frac{RT}{F} = 0.059 \text{)}$ Source: orcusprep.in

NEET 2017

medium

$E_1 < E_2$

$E_1 > E_2$

$E_2 = 0 \ne E_1$

$E_1 = E_2$

Q19. If the $E^\circ_{\text{cell}}$ for a given reaction has a negative value, which of the following gives the correct relationships for the values of $\Delta G^\circ$ and $K_{\text{eq}}$ ? Source: orcusprep.in

NEET 2016

easy

$\Delta G^\circ > 0$; $K_{\text{eq}} < 1$

$\Delta G^\circ > 0$; $K_{\text{eq}} > 1$

$\Delta G^\circ < 0$; $K_{\text{eq}} > 1$

$\Delta G^\circ < 0$; $K_{\text{eq}} < 1$

Q20. The pressure of $\text{H}_2$ required to make the potential of $\text{H}_2$ electrode zero in pure water at $298 \text{ K}$ is Source: orcusprep.in

NEET 2016

medium

$10^{-10} \text{ atm}$

$10^{-4} \text{ atm}$

$10^{-14} \text{ atm}$

$10^{-12} \text{ atm}$.

Q21. A hydrogen gas electrode is made by dipping platinum wire in a solution of $\text{HCl}$ of $\text{pH} = 10$ and by passing hydrogen gas around the platinum wire at one $\text{atm}$ pressure. The oxidation potential of electrode would be Source: orcusprep.in

NEET 2013

medium

0.118 V

1.18 V

0.059 V

0.59 V

Q22. Consider the half-cell reduction reaction $\text{Mn}^{2+} + 2e^{-} \to \text{Mn}$, $E^\circ = - 1.18 \text{ V}$ and $\text{Mn}^{2+} \to \text{Mn}^{3+} + e^{-}$, $E^\circ = - 1.51 \text{ V}$. The $E^\circ$ for the reaction, $3\text{Mn}^{2+} \to \text{Mn}^{0} + 2\text{Mn}^{3+}$, and possibility of the forward reaction are respectively Source: orcusprep.in

NEET 2013

hard

$- 4.18 \text{ V}$ and yes

$+ 0.33 \text{ V}$ and yes

$+ 2.69 \text{ V}$ and no

$- 2.69 \text{ V}$ and no.

Q23. The Gibbs’ energy for the decomposition of $\text{Al}_2\text{O}_3$ at $500 \circ\text{C}$ is as follows $\frac{2}{3}\text{Al}_2\text{O}_3 \to \frac{4}{3}\text{Al} + \text{O}_2$, $\Delta_{\text{r}}G = + 960 \text{ kJ mol}^{-1}$. The potential difference needed for the electrolytic reduction of aluminium oxide ($\text{Al}_2\text{O}_3$) at $500 \circ\text{C}$ is at least Source: orcusprep.in

AIPMT Mains 2012

medium

4.5 V

3.0 V

2.5 V

5.0 V

Q24. The electrode potentials for, $\text{Cu}^{2+}(\text{aq}) + e^{-} \to \text{Cu}^{+}(\text{aq})$ and $\text{Cu}^{+}(\text{aq}) + e^{-} \to \text{Cu}(s)$ are $\mathbf{+ 0.15 \text{ V}}$ and $\mathbf{+ 0.50 \text{ V}}$ respectively. The value of $E^\circ_{\text{Cu}^{2+}/\text{Cu}}$ will be Source: orcusprep.in

AIPMT 2011

medium

0.500 V

0.325 V

0.650 V

0.150 V

Q25. For the reduction of silver ions with copper metal, the standard cell potential was found to be $+ 0.46 \text{ V}$ at $25 \circ\text{C}$. The value of standard Gibbs energy, $\Delta G^\circ$ will be $\text{ (F = 96500 } \text{ C mol}^{-1})$ Source: orcusprep.in

AIPMT 2010

easy

$- 89.0 \text{ kJ}$

$- 89.0 \text{ J}$

$- 44.5 \text{ kJ}$

$- 98.0 \text{ kJ}$

Q26. Given : (i) $\text{Cu}^{2+} + 2e^{-} \to \text{Cu}$, $E^\circ = 0.337 \text{ V}$. (ii) $\text{Cu}^{2+} + e^{-} \to \text{Cu}^{+}$, $E^\circ = 0.153 \text{ V}$. Electrode potential, $E^\circ$ for the reaction, $\text{Cu}^{+} + e^{-} \to \text{Cu}$, will be Source: orcusprep.in

AIPMT 2009

medium

0.90 V

0.30 V

0.38 V

0.52 V

Q27. Standard free energies of formation (in $\text{kJ/mol}$) at $298 \text{ K}$ are $\mathbf{-237.2}$, $\mathbf{-394.4}$ and $\mathbf{-8.2}$ for $\text{H}_2\text{O}(l)$, $\text{CO}_2(g)$ and pentane($g$) respectively. The value of $E^\circ_{\text{cell}}$ for the pentane-oxygen fuel cell is Source: orcusprep.in

AIPMT 2008

hard

1.0968 V

0.0968 V

1.968 V

2.0968 V

Q28. The equilibrium constant of the reaction : $\text{Cu}(s) + 2\text{Ag}^{+}(\text{aq}) \to \text{Cu}^{2+}(\text{aq}) + 2\text{Ag}(s)$; $E^\circ = 0.46 \text{ V}$ at $298 \text{ K}$ is Source: orcusprep.in

AIPMT 2007

medium

$2.0 \times 10^{10}$

$4.0 \times 10^{10}$

$4.0 \times 10^{15}$

$2.4 \times 10^{10}$

Q29. The standard $\text{e.m.f.}$ of a galvanic cell involving cell reaction with $n = 2$ is found to be $\mathbf{0.295 \text{ V}}$ at $25^\circ\text{C}$. The equilibrium constant of the reaction would be $\text{ (Given } F = 96500 \text{ C mol}^{-1}, R = 8.314 \text{ J K}^{-1} \text{ mol}^{-1})$ Source: orcusprep.in

AIPMT 2004

medium

$2.0 \times 10^{11}$

$4.0 \times 10^{12}$

$1.0 \times 10^{2}$

$1.0 \times 10^{10}$

Q30. On the basis of the information available from the reaction, $\frac{4}{3}\text{Al} + \text{O}_2 \to \frac{2}{3}\text{Al}_2\text{O}_3$, $\Delta G = -827 \text{ kJ mol}^{-1}$ of $\text{O}_2$, the minimum $\text{e.m.f.}$ required to carry out an electrolysis of $\text{Al}_2\text{O}_3$ is $\text{ (F = 96500 } \text{ C mol}^{-1})$ Source: orcusprep.in

AIPMT 2003

medium

2.14 V

4.28 V

6.42 V

8.56 V

Q31. For the disproportionation of copper $2\text{Cu}^{+} \to \text{Cu}^{2+} + \text{Cu}$, $E^\circ$ is $\text{ (Given } E^\circ \text{ for } \text{Cu}^{2+}/\text{Cu} \text{ is } 0.34 \text{ V } \text{ and } E^\circ \text{ for } \text{Cu}^{2+}/\text{Cu}^{+} \text{ is } 0.15 \text{ V)}$ Source: orcusprep.in

AIPMT 2000

medium

0.49 V

$-0.19 \text{ V}$

0.38 V

$-0.38 \text{ V}$

Q32. $E^\circ$ for the cell, $\text{Zn} | \text{Zn}^{2+}(\text{aq}) ||\text{Cu}^{2+}(\text{aq}) | \text{Cu}$ is $\mathbf{1.10 \text{ V}}$ at $25^\circ\text{C}$, the equilibrium constant for the reaction $\text{Zn} + \text{Cu}^{2+}(\text{aq}) \to \text{Cu} + \text{Zn}^{2+}(\text{aq})$ is of the order Source: orcusprep.in

AIPMT 1997

medium

$10^{+18}$

$10^{+17}$

$10^{-28}$

$10^{+37}$

Q33. Following limiting molar conductivities are given as : $\lambda^\circ_{\text{m}}(\text{H}_2\text{SO}_4) = x \text{ S cm}^2 \text{ mol}^{-1}$; $\lambda^\circ_{\text{m}}(\text{K}_2\text{SO}_4) = y \text{ S cm}^2 \text{ mol}^{-1}$; $\lambda^\circ_{\text{m}}(\text{CH}_3\text{COOK}) = z \text{ S cm}^2 \text{ mol}^{-1}$. $\lambda^\circ_{\text{m}} \text{ (in } \text{S cm}^2 \text{ mol}^{-1})$ for $\text{CH}_3\text{COOH}$ will be Source: orcusprep.in

NEET 2019

medium

x - y + 2z

x + y - z

x - y + z

$\frac{x - y}{2} + z$

Q34. The molar conductivity of a $\mathbf{0.5 \text{ mol/dm}^3}$ solution of $\text{AgNO}_3$ with electrolytic conductivity of $\mathbf{5.76 \times 10^{-3} \text{ S cm}^{-1}}$ at $298 \text{ K}$ is Source: orcusprep.in

NEET 2016

easy

2.88 $\text{S cm}^2/\text{mol}$

11.52 $\text{S cm}^2/\text{mol}$

0.086 $\text{S cm}^2/\text{mol}$

28.8 $\text{S cm}^2/\text{mol}$

Q35. At $25 \circ\text{C}$ molar conductance of $0.1 \text{ molar}$ aqueous solution of ammonium hydroxide is $\mathbf{9.54 \text{ ohm}^{-1} \text{ cm}^2 \text{ mol}^{-1}}$ and at infinite dilution its molar conductance is $\mathbf{238 \text{ ohm}^{-1} \text{ cm}^2 \text{ mol}^{-1}}$. The degree of ionisation of ammonium hydroxide at the same concentration and temperature is Source: orcusprep.in

NEET 2013

easy

4.008%

40.800%

2.080%

20.800%

Q36. Limiting molar conductivity of $\text{NH}_4\text{OH}$ [i.e., $L^\circ_{\text{m}}(\text{NH}_4\text{OH})$] is equal to Source: orcusprep.in

AIPMT 2012

easy

$L^\circ_{\text{m}}(\text{NH}_4\text{Cl}) + L^\circ_{\text{m}}(\text{NaCl}) - L^\circ_{\text{m}}(\text{NaOH})$

$L^\circ_{\text{m}}(\text{NaOH}) + L^\circ_{\text{m}}(\text{NaCl}) - L^\circ_{\text{m}}(\text{NH}_4\text{Cl})$

$L^\circ_{\text{m}}(\text{NH}_4\text{OH}) + L^\circ_{\text{m}}(\text{NH}_4\text{Cl}) - L^\circ_{\text{m}}(\text{HCl})$

$L^\circ_{\text{m}}(\text{NH}_4\text{Cl}) + L^\circ_{\text{m}}(\text{NaOH}) - L^\circ_{\text{m}}(\text{NaCl})$

Q37. Molar conductivities (L°m) at infinite dilution of $\text{NaCl}$, $\text{HCl}$ and $\text{CH}_3\text{COONa}$ are $\mathbf{126.4}$, $\mathbf{425.9}$ and $\mathbf{91.0 \text{ S cm}^2 \text{ mol}^{-1}}$ respectively. $(L^\circ_{\text{m}})$ for $\text{CH}_3\text{COOH}$ will be Source: orcusprep.in

AIPMT Mains 2012

easy

425.5 $\text{S cm}^2 \text{ mol}^{-1}$

180.5 $\text{S cm}^2 \text{ mol}^{-1}$

290.8 $\text{S cm}^2 \text{ mol}^{-1}$

390.5 $\text{S cm}^2 \text{ mol}^{-1}$

Q38. An increase in equivalent conductance of a strong electrolyte with dilution is mainly due to Source: orcusprep.in

AIPMT 2010

medium

increase in ionic mobility of ions

$100\%$ ionisation of electrolyte at normal dilution

increase in both i.e., number of ions and ionic mobility of ions

increase in number of ions.

Q39. Which of the following expressions correctly represents the equivalent conductance at infinite dilution of $\text{Al}_2(\text{SO}_4)_3$? Given that $\Lambda^\circ_{\text{eq}, \text{Al}^{3+}}$ and $\Lambda^\circ_{\text{eq}, \text{SO}_4^{2-}}$ are the equivalent conductances at infinite dilution of the respective ions. Source: orcusprep.in

AIPMT Mains 2010

easy

$2\Lambda^\circ_{\text{eq}, \text{Al}^{3+}} + 3\Lambda^\circ_{\text{eq}, \text{SO}_4^{2-}}$

$\Lambda^\circ_{\text{eq}, \text{Al}^{3+}} + \Lambda^\circ_{\text{eq}, \text{SO}_4^{2-}}$

$(\Lambda^\circ_{\text{eq}, \text{Al}^{3+}} + \Lambda^\circ_{\text{eq}, \text{SO}_4^{2-}}) \times 6$

$\frac{1}{3} \Lambda^\circ_{\text{eq}, \text{Al}^{3+}} + \frac{1}{2} \Lambda^\circ_{\text{eq}, \text{SO}_4^{2-}}$

Q40. The equivalent conductance of $\text{M}/32$ solution of a weak monobasic acid is $\mathbf{8.0 \text{ mho cm}^2}$ and at infinite dilution is $\mathbf{400 \text{ mho cm}^2}$. The dissociation constant of this acid is Source: orcusprep.in

AIPMT 2009

medium

$1.25 \times 10^{-6}$

$6.25 \times 10^{-4}$

$1.25 \times 10^{-4}$

$1.25 \times 10^{-5}$

Q41. Kohlrausch’s law states that at Source: orcusprep.in

AIPMT 2008

easy

infinite dilution, each ion makes definite contribution to conductance of an electrolyte whatever be the nature of the other ion of the electrolyte

infinite dilution, each ion makes definite contribution to equivalent conductance of an electrolyte, whatever be the nature of the other ion of the electrolyte

finite dilution, each ion makes definite contribution to equivalent conductance of an electrolyte, whatever be the nature of the other ion of the electrolyte

infinite dilution each ion makes definite contribution to equivalent conductance of an electrolyte depending on the nature of the other ion of the electrolyte.

Q42. Equivalent conductances of $\text{Ba}^{2+}$ and $\text{Cl}^{-}$ ions are $\mathbf{127}$ and $\mathbf{76 \text{ ohm}^{-1} \text{ cm}^{-1} \text{ eq}^{-1}}$ respectively. Equivalent conductance of $\text{BaCl}_2$ at infinite dilution is Source: orcusprep.in

AIPMT 2000

easy

139.5

101.5

203

279

Q43. The specific conductance of a $\mathbf{0.1 \text{ N} \text{ KCl}}$ solution at $23^\circ\text{C}$ is $\mathbf{0.012 \text{ ohm}^{-1} \text{ cm}^{-1}}$. The resistance of cell containing the solution at the same temperature was found to be $\mathbf{55 \text{ ohm}}$. The cell constant will be Source: orcusprep.in

AIPMT 1999

easy

$0.918 \text{ cm}^{-1}$

$0.66 \text{ cm}^{-1}$

$1.142 \text{ cm}^{-1}$

$1.12 \text{ cm}^{-1}$

Q44. On heating one end of a piece of a metal, the other end becomes hot because of Source: orcusprep.in

AIPMT 1995

easy

energised electrons moving to the other end

minor perturbation in the energy of atoms

resistance of the metal

mobility of atoms in the metal.

Q45. On electrolysis of dil. sulphuric acid using platinum (Pt) electrode, the product obtained at anode will be Source: orcusprep.in

NEET 2020

easy

hydrogen gas

oxygen gas

$\text{H}_2\text{S}$ gas

$\text{SO}_2$ gas.

Q46. The number of Faradays ($ ext{F}$) required to produce $\mathbf{20 \text{ g}}$ of calcium from molten $\text{CaCl}_2$ (Atomic mass of $\text{Ca} = 40 \text{ g mol}^{-1}$) is Source: orcusprep.in

NEET 2020

easy

1

2

3

4

Q47. During the electrolysis of molten sodium chloride, the time required to produce $\mathbf{0.10 \text{ mol}}$ of chlorine gas using a current of $\mathbf{3 \text{ amperes}}$ is Source: orcusprep.in

NEET 2016

medium

55 minutes

110 minutes

220 minutes

330 minutes.

Q48. The number of electrons delivered at the cathode during electrolysis by a current of $\mathbf{1 \text{ ampere}}$ in $\mathbf{60 \text{ seconds}}$ is ($ ext{charge on electron} = 1.60 \times 10^{-19} \text{ C}$) Source: orcusprep.in

NEET 2016

easy

$6 \times 10^{23}$

$6 \times 10^{20}$

$3.75 \times 10^{20}$

$7.48 \times 10^{23}$

Q49. When $\mathbf{0.1 \text{ mol } \text{MnO}_4^{2-}}$ is oxidised, the quantity of electricity required to completely oxidise $\text{MnO}_4^{2-}$ to $\text{MnO}_4^{-}$ is Source: orcusprep.in

AIPMT 2014

medium

96500 C

$2 \times 96500 \text{ C}$

9650 C

96.50 C

Q50. The weight of silver (at. wt. = 108) displaced by a quantity of electricity which displaces $\mathbf{5600 \text{ mL}}$ of $\text{O}_2$ at $\text{STP}$ will be Source: orcusprep.in

AIPMT 2014

hard

5.4 g

10.8 g

54.0 g

108.0 g

Q51. How many grams of cobalt metal will be deposited when a solution of cobalt(II) chloride is electrolyzed with a current of $\mathbf{10 \text{ amperes}}$ for $\mathbf{109 \text{ minutes}}$? $\text{ (1 Faraday = 96,500 } \text{ C}; \text{ Atomic mass of } \text{Co} = 59 \text{ u)}$ Source: orcusprep.in

NEET 2013

medium

4.0

20.0

40.0

0.66

Q52. $\mathbf{4.5 \text{ g}}$ of aluminium (at. mass $\mathbf{27 \text{ amu}}$) is deposited at cathode from $\text{Al}^{3+}$ solution by a certain quantity of electric charge. The volume of hydrogen produced at $\text{STP}$ from $\text{H}^{+}$ ions in solution by the same quantity of electric charge will be Source: orcusprep.in

AIPMT 2005

medium

44.8 L

22.4 L

11.2 L

5.6 L

Q53. In electrolysis of $\text{NaCl}$ when $\text{Pt}$ electrode is taken then $\text{H}_2$ is liberated at cathode while with $\text{Hg}$ cathode it forms sodium amalgam. The reason for this is Source: orcusprep.in

AIPMT 2002

medium

$\text{Hg}$ is more inert than $\text{Pt}$

more voltage is required to reduce $\text{H}^{+}$ at $\text{Hg}$ than at $\text{Pt}$

$\text{Na}$ is dissolved in $\text{Hg}$ while it does not dissolve in $\text{Pt}$

conc. of $\text{H}^{+}$ ions is larger when $\text{Pt}$ electrode is taken.

Q54. A $\mathbf{5 \text{ ampere}}$ current is passed through a solution of zinc sulphate for $\mathbf{40 \text{ minutes}}$. The amount of zinc deposited at the cathode is Source: orcusprep.in

AIPMT 1996

medium

0.4065 g

65.04 g

40.65 g

4.065 g

Q55. Sodium is made by the electrolysis of a molten mixture of about $\mathbf{40\% \text{ NaCl}}$ and $\mathbf{60\% \text{ CaCl}_2}$ because Source: orcusprep.in

AIPMT 1995

easy

$\text{Ca}^{++}$ can reduce $\text{NaCl}$ to $\text{Na}$

$\text{Ca}^{++}$ can displace $\text{Na}$ from $\text{NaCl}$

$\text{CaCl}_2$ helps in conduction of electricity

this mixture has a lower melting point than $\text{NaCl}$.

Q56. When $\text{CuSO}_4$ is electrolysed using platinum electrodes, Source: orcusprep.in

AIPMT 1993

easy

copper is liberated at cathode, sulphur at anode

copper is liberated at cathode, oxygen at anode

sulphur is liberated at cathode, oxygen at anode

oxygen is liberated at cathode, copper at anode.

Q57. On electrolysis of dilute sulphuric acid using platinum electrodes, the product obtained at the anode will be Source: orcusprep.in

AIPMT 1992

easy

hydrogen

oxygen

hydrogen sulphide

sulphur dioxide.

Q58. A device that converts energy of combustion of fuels like hydrogen and methane, directly into electrical energy is known as Source: orcusprep.in

AIPMT 2015

easy

dynamo

Ni-Cd cell

fuel cell

electrolytic cell.

Q59. The efficiency of a fuel cell is given by Source: orcusprep.in

AIPMT 2007

easy

$\Delta G/\Delta S$

$\Delta G/\Delta H$

$\Delta S/\Delta G$

$\Delta H/\Delta G$

Q60. Zinc can be coated on iron to produce galvanized iron but the reverse is not possible. It is because Source: orcusprep.in

NEET 2016

medium

zinc is lighter than iron

zinc has lower melting point than iron

zinc has lower negative electrode potential than iron

zinc has higher negative electrode potential than iron.

Q61. The most convenient method to protect the bottom of ship made of iron is Source: orcusprep.in

AIPMT 2001

easy

coating it with red lead oxide

white tin plating

connecting it with $\text{Mg}$ block

connecting it with $\text{Pb}$ block.

Q62. To protect iron against corrosion, the most durable metal plating on it, is Source: orcusprep.in

AIPMT 1991

medium

copper plating

zinc plating

nickel plating

tin plating.

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Chemistry - Electrochemistry-PYQ

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Chemistry - Electrochemistry-PYQ

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