Q 1 :

One of the commonly used electrodes is calomel electrode. Under which of the following categories calomel electrode come?          [2024]

• Metal ion – Metal electrodes

   

• Oxidation – Reduction electrodes

   

• Metal – Insoluble Salt – Anion electrodes

   

• Gas – Ion electrodes

   

Q 2 :

How can an electrochemical cell be converted into an electrolytic cell?

• Reversing the flow of ions in salt bridge.

   

• Applying an external opposite potential greater than $E_{\text{cell}}^0$.

   

• Exchanging the electrodes at anode and cathode.

   

• Applying an external opposite potential lower than $E_{\text{cell}}^0$.

   

Q 3 :

Reduction potential of ions are given below:

     ${\mathrm{ClO}}_4^{-}$                         ${\mathrm{IO}}_4^{-}$                             ${\mathrm{BrO}}_4^{-}$

${\mathrm{E}}^{°}=1.19\mathrm{V}$         ${\mathrm{E}}^{°}=1.65\mathrm{V}$             ${\mathrm{E}}^{°}=1.74\mathrm{V}$

The correct order of their oxidising power is:                   [2024]

• ${\mathrm{ClO}}_4^{-}>{\mathrm{IO}}_4^{-}>{\mathrm{BrO}}_4^{-}$

   

• ${\mathrm{BrO}}_4^{-}>{\mathrm{IO}}_4^{-}>{\mathrm{ClO}}_4^{-}$

   

• ${\mathrm{BrO}}_4^{-}>{\mathrm{ClO}}_4^{-}>{\mathrm{IO}}_4^{-}$

   

• ${\mathrm{IO}}_4^{-}>{\mathrm{BrO}}_4^{-}>{\mathrm{ClO}}_4^{-}$

   

Q 4 :

Match List I with List II.

	List I		List II
	(Cell)		(Use/Property/Reaction)
A.	Leclanche cell	I.	Converts energy of combustion into electrical energy
B.	Ni-Cd cell	II.	Does not involve any ion in solution and is used in hearing aids
C.	Fuel cell	III.	Rechargeable
D.	Mercury cell	IV.	Reaction at anode $\text{Zn}\to {\text{Zn}}^{2+}+2{\text{e}}^{-}$

 

Choose the correct answer from the options given below:                    [2024]

• A–II, B–III, C–IV, D–I

   

• A–III, B–I, C–IV, D–II

   

• A–I, B–II, C–III, D–IV

   

• A–IV, B–III, C–I, D–II

   

Q 5 :

The standard reduction potentials at 298 K for the following half cells are given below:                           [2024]

$C{r}_2{O}_7^{2-}+14H^{+}+6e^{-}\to 2C{r}^{3+}+7H_{2}O, E^0=1.33V$

$F{e}^{3+}\left(aq\right)+3e^{-}\to Fe, E^0=-0.04V$

$N{i}^{2+}\left(aq\right)+2e^{-}\to Ni, E^0=-0.25V$

$A{g}^{+}\left(aq\right)+e^{-}\to Ag, E^0=0.80V$

$A{u}^{3+}\left(aq\right)+3e^{-}\to Au, E^0=1.40V$

Consider the given electrochemical reactions,

The number of metal(s) which will be oxidized be $C{r}_2{O}_7^{2-}$ in aqueous solution is __________.

Q 6 :

${\mathrm{FeO}}_4^{2-}\stackrel{+\text{2.0 V}}{\to }{\mathrm{Fe}}^{3+}\stackrel{\text{0.8 V}}{\to }{\mathrm{Fe}}^{2+}\stackrel{-\text{0.5 V}}{\to }{\mathrm{Fe}}^0$

In the above diagram, the standard electrode potentials are given in volts (over the arrow).

The value of  ${\mathrm{E}}_{{\mathrm{FeO}}_4^{2-}/{\mathrm{Fe}}^{2+}}^{⊝}$  is                           [2025]

• 2.1 V

   

• 1.7 V

   

• 1.2 V

   

• 1.4 V

   

Q 7 :

For the given cell

${\mathrm{Fe}}^{2+}{}_{\left(\mathrm{aq}\right)}+{{\mathrm{Ag}}^{+}}_{\left(\mathrm{aq}\right)}\to {{\mathrm{Fe}}^{3+}}_{\left(\mathrm{aq}\right)}+{\mathrm{Ag}}_{\left(\mathrm{s}\right)}$

The standard cell potential of the above reaction is:

Given:

${\mathrm{Ag}}^{+}+{\mathrm{e}}^{-}\to \mathrm{Ag}$           ${\mathrm{E}}^{\mathrm{\theta }}=\text{x\hspace{0.05em}V}$ 

${\mathrm{Fe}}^{2+}+2{\mathrm{e}}^{-}\to \mathrm{Fe}$       ${\mathrm{E}}^{\mathrm{\theta }}=\text{y\hspace{0.05em}V}$ 

${\mathrm{Fe}}^{3+}+3{\mathrm{e}}^{-}\to \mathrm{Fe}$        ${\mathrm{E}}^{\mathrm{\theta }}=\text{z\hspace{0.05em}V}$                       [2025]

• $x+2y-3z$

   

• $x+2y$

   

• $x+y-z$

   

• $y-2x$

   

Q 8 :

Based on the data given below:

${\mathrm{E}}_{{\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}/{\mathrm{Cr}}^{3+}}^{\circ }=\text{1.33\hspace{0.05em}V} {\mathrm{E}}_{{\mathrm{Cl}}_2/{\mathrm{Cl}}^{-}}^{\circ }=\text{1.36\hspace{0.05em}V}$

${\mathrm{E}}_{{\mathrm{MnO}}_4^{-}/{\mathrm{Mn}}^{2+}}^{\circ }=\text{1.51\hspace{0.05em}V} {\mathrm{E}}_{{\mathrm{Cr}}^{3+}/\mathrm{Cr}}^{\circ }=-\text{0.74\hspace{0.05em}V}$

The strongest reducing agent is:                               [2025]

• ${\mathrm{Mn}}^{2+}$

   

• ${\mathrm{Cl}}^{-}$

   

• ${\mathrm{MnO}}_4^{-}$

   

• $\mathrm{Cr}$

   

Q 9 :

The standard reduction potential values of some of the $p$-block ions are given below. Predict the one with the strongest oxidising capacity.         [2025]

• ${\mathrm{E}}_{{\mathrm{Sn}}^{4+}/{\mathrm{Sn}}^{2+}}^{⊝}=+\text{1.15\hspace{0.05em}V}$

   

• ${\mathrm{E}}_{{\mathrm{Pb}}^{4+}/{\mathrm{Pb}}^{2+}}^{⊝}=+\text{1.67\hspace{0.05em}V}$

   

• ${\mathrm{E}}_{{\mathrm{Tl}}^{3+}/\mathrm{Tl}}^{⊝}=+\text{1.26\hspace{0.05em}V}$

   

• ${\mathrm{E}}_{{\mathrm{Al}}^{3+}/\mathrm{Al}}^{⊝}=-\text{1.66\hspace{0.05em}V}$

   

Q 10 :

The standard electrode potential $({\mathrm{M}}^{3+}/{\mathrm{M}}^{2+})$ for V, Cr, Mn and Co are - 0.26 V, - 0.41 V, + 1.57 V and + 1.97 V, respectively. The metal ions which can liberate ${\mathrm{H}}_2$ from a dilute acid are            [2023]
 

• ${\mathrm{V}}^{2+}$ and ${\mathrm{Mn}}^{2+}$

   

• ${\mathrm{Mn}}^{2+}$ and ${\mathrm{Co}}^{2+}$

   

• ${\mathrm{Cr}}^{2+}$ and ${\mathrm{Co}}^{2+}$

   

• ${\mathrm{V}}^{2+}$ and ${\mathrm{Cr}}^{2+}$

   

Q 11 :

The standard electrode potential of ${\mathrm{M}}^{+}/\mathrm{M}$ in aqueous solution does not depend on           [2023]

• Sublimation of a solid metal

   

• Ionisation of a solid metal atom

   

• Hydration of a gaseous metal ion

   

• Ionisation of a gaseous metal atom

   

Q 12 :

The reaction

$\frac{1}{2}{\mathrm{H}}_2\left(\mathrm{g}\right)+\mathrm{AgCl}\left(\mathrm{s}\right)\rightleftharpoons {\mathrm{H}}^{+}\left(\mathrm{aq}\right)+{\mathrm{Cl}}^{-}\left(\mathrm{aq}\right)+\mathrm{Ag}\left(\mathrm{s}\right)$

occurs in which of the given galvanic cells?                        [2023]

• $\mathrm{Pt}\left|{\mathrm{H}}_2\right(\mathrm{g}\left)\right|\mathrm{HCl}\left({\mathrm{sol}}^{\mathrm{n}}\right)\left|\mathrm{AgCl}\right(\mathrm{s}\left)\right|\mathrm{Ag}$

   

• $\mathrm{Ag}\left|\mathrm{AgCl}\right(\mathrm{s}\left)\right|\mathrm{KCl}\left({\mathrm{sol}}^{\mathrm{n}}\right)\left|{\mathrm{AgNO}}_3\right|\mathrm{Ag}$

   

• $\mathrm{Pt}\left|{\mathrm{H}}_2\right(\mathrm{g}\left)\right|\mathrm{HCl}\left({\mathrm{sol}}^{\mathrm{n}}\right)\left|{\mathrm{AgNO}}_3\right({\mathrm{sol}}^{\mathrm{n}}\left)\right|\mathrm{Ag}$

   

• $\mathrm{Pt}\left|{\mathrm{H}}_2\right(\mathrm{g}\left)\right|\mathrm{KCl}\left({\mathrm{sol}}^{\mathrm{n}}\right)\left|\mathrm{AgCl}\right(\mathrm{s}\left)\right|\mathrm{Ag}$

   

Q 13 :

The standard reduction potentials at 298 K for the following half cells are given below:

${\text{NO}}_3^{-}+4{\text{H}}^{+}+3e^{-}\to \text{NO(g)}+2{\text{H}}_2\text{O}$     $E^{\mathit{\theta }}=0.97\text{ V}$

${\text{V}}^{2+}\left(aq\right)+2e^{-}\to \text{V}$                                   $E^{\mathit{\theta }}=-1.19\text{ V}$

${\text{Fe}}^{3+}\left(aq\right)+3e^{-}\to \text{Fe}$                               $E^{\mathit{\theta }}=-0.04\text{ V}$

${\text{Ag}}^{+}\left(aq\right)+e^{-}\to \text{Ag(s)}$                             $E^{\mathit{\theta }}=0.80\text{ V}$

${\text{Au}}^{3+}\left(aq\right)+3e^{-}\to \text{Au(s)}$                         $E^{\mathit{\theta }}=1.40\text{ V}$

The number of metal(s) which will be oxidized by ${\mathrm{NO}}_3^{-}$ in aqueous solution is _____________ .          [2023]

Q 14 :

At 298 K, the standard reduction potential for the ${\mathrm{Cu}}^{2+}/\mathrm{Cu}$ electrode is 0.34 V.

$\text{Given: }{K}_{sp}{\text{Cu(OH)}}_{\mathit{2}}=1\times {10}^{-20}$

$\text{Take }\frac{2.303RT}{F}=0.059\text{ V}$

The reduction potential at pH = 14 for the above couple is $(-)x\times {10}^{-2}$V. The value of $x$  is __________ .        [2023]

Q 15 :

Consider the following electrochemical cell at 298 K:

$\text{Pt }\left|{\text{ HSnO}}_2^{-}\right(aq\left)\right|\text{ Sn}{\left(\mathrm{OH}\right)}_6^{2-}\left(aq\right)\left|{\text{ OH}}^{-}\right(aq\left)\right|{\text{ Bi}}_2{\text{O}}_3\left(s\right)\left|\text{ Bi}\right(s)$

If the reaction quotient at a given time is ${10}^6$, then the cell EMF $\left(E_{\text{cell}}\right)$ is __________$\times {10}^{-1}\text{ V}$ (Nearest integer).

Given the standard half-cell reduction potentials as:

$E_{{\text{Bi}}_2{\text{O}}_3/\text{Bi}, {\text{OH}}^{-}}^{\circ }=-0.44\text{ V}$ and $E_{{\text{Sn(OH)}}_6^{2-}/{\text{HSnO}}_2^{-}, {\text{OH}}^{-}}^{\circ }=-0.90\text{ V}$                 [2026]

Q 16 :

Consider the following reduction processes:

${\mathrm{Al}}^{3+}+3{\mathrm{e}}^{-}⟶\mathrm{Al}\left(\mathrm{s}\right), E°=-1.66 \text{V}$ 

${\mathrm{Fe}}^{3+}+{\mathrm{e}}^{-}⟶{\mathrm{Fe}}^{2+}, E°=+0.77 \text{V}$

${\mathrm{Co}}^{3+}+{\mathrm{e}}^{-}⟶{\mathrm{Co}}^{2+}, E°=+1.81 \text{V}$

${\mathrm{Cr}}^{3+}+3{\mathrm{e}}^{-}⟶\mathrm{Cr}\left(\mathrm{s}\right), E°=-0.74 \text{V}$

The tendency to act as reducing agent decreases in the order:              [2026]

• $\mathrm{Al}>{\mathrm{Fe}}^{2+}>\mathrm{Cr}>{\mathrm{Co}}^{2+}$

   

• $\mathrm{Al}>\mathrm{Cr}>{\mathrm{Co}}^{2+}>{\mathrm{Fe}}^{2+}$

   

• $\mathrm{Cr}>{\mathrm{Fe}}^{2+}>\mathrm{Al}>{\mathrm{Co}}^{2+}$

   

• $\mathrm{Al}>\mathrm{Cr}>{\mathrm{Fe}}^{2+}>{\mathrm{Co}}^{2+}$

   

Q 17 :

Electrolysis of aqueous $CuS{O}_4(0.1M)$ was carried out is two cells I and II. In I, the electrodes are of Cu and is II they were of Pt. As the electrolysis proceeds pH of the electrolyte solution will

• decrease is II and remain the same in I

   

• remain the same in both I and II

   

• increase in both I and II

   

• increase in I and decrease is II

   

Q 18 :

Saturated solution of $KN{O}_3$ with agar-agar is used to make 'salt bridge' because:

• size of $K^{+}$ is greater than that of $N{O}_3^{-}$

   

• velocity of $N{O}_3^{-}$ is greater than that of $K^{+}$

   

• velocities of both $K^{+}$ and $N{O}_3^{-}$ are nearly the same

   

• both velocities and size of $K^{+}$ and $N{O}_3^{-}$ ions are same