Redox Reactions and Electrochemistry — JEE Main PYQs

The solubility product of a sparingly soluble salt ${\mathrm{A}}_2{\mathrm{X}}_3$ is $1.1\times 10^{-23}$. If specific conductance of the solution is $3\times 10^{-5}\mathrm{S}{\mathrm{m}}^{-1}$, the limiting molar conductivity of the solution is …

The quantity of electricity in Faraday needed to reduce 1 mol of ${\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}$ to ${\mathrm{Cr}}^{3+}$ is ______.

The cell potential for the given cell at 298 K
$\mathrm{Pt}\left|{\mathrm{H}}_2(\mathrm{g},1\mathrm{bar})\right|{\mathrm{H}}^{+}(\mathrm{aq})\Vert {\mathrm{Cu}}^{2+}(\mathrm{aq})\mid \mathrm{Cu}(\mathrm{s})$
is 0.31 V. The pH of the acidic solution is found to be 3, whereas the co …

Which one of the following is an example of disproportionation reaction?

$\mathrm{Cu}(\mathrm{s})+{\mathrm{Sn}}^{2+}(0.001\mathrm{M})\to {\mathrm{Cu}}^{2+}(0.01\mathrm{M})+\mathrm{Sn}(\mathrm{s})$

The Gibbs free energy change for the above reaction at 298 K is $\mathrm{x}\times 10^{-1}\mathrm{kJ}{\mathrm{mol}}^{-1}$;

The value of $x$ is …

A dilute solution of sulphuric acid is electrolysed using a current of 0.10 A for 2 hours to produce hydrogen and oxygen gas. The total volume of gases produced at STP is ______ ${\mathrm{cm}}^3$. (Nearest integer)
[Given: Faraday constant F $=96500{\mathrm{C}\mathrm{mol}}^{-1}$
at STP, …

The ${\left(\frac{\partial E}{\partial T}\right)}_P$ of four different types of half cells are as follows (in $\mathrm{V}{\mathrm{K}}^{-1}$): A $=1\times 10^{-4}$, B $=2\times 10^{-4}$, C $=0.1\times 10^{-4}$, D $=0.2\times 10^{-4}$ (where E is the electromotive force). Which of the above ha …

The limiting molar conductivities of $\mathrm{NaI},{\mathrm{NaNO}}_3$ and ${\mathrm{AgNO}}_3$ are 12.7, 12.0 and $13.3\mathrm{mS}{\mathrm{m}}^2{\mathrm{mol}}^{-1}$, respectively (all at $25^{\circ }\mathrm{C}$ ). The limiting molar conductivity of AgI at this temperatu …

Resistance of a conductivity cell (cell constant $129{\mathrm{m}}^{-1}$) filled with 74.5 ppm solution of KCl is $100\Omega$ (labelled as solution 1). When the same cell is filled with KCl solution of 149 ppm, the resistance is $50\Omega$ (labelled as solution 2). The ratio of …

The cell potential for the following cell
Pt|H₂(g)|H⁺(aq)||Cu²⁺(0.01 M)|Cu(s)
is 0.576 V at 298 K. The pH of the solution is ______. (Nearest integer)

The resistance of conductivity cell containing 0.01 M KCl solution at 298 K is $1750\Omega$. If the conductivity of 0.01 M KCl solution at 298 K is $0.152\times 10^{-3}\mathrm{S}{\mathrm{cm}}^{-1}$, then the cell constant of the conductivity cell is _____ …

The correct order of reduction potentials of the following pairs is
A. ${\mathrm{Cl}}_2/{\mathrm{Cl}}^{-}$
B. ${\mathrm{I}}_2/{\mathrm{I}}^{-}$
C. ${\mathrm{Ag}}^{+}/\mathrm{Ag}$
D. ${\mathrm{Na}}^{+}/\mathrm{Na}$
E. ${\mathrm{Li}}^{+}/\mathrm{Li}$

Choose the correct answer from …

A solution of ${\mathrm{Fe}}_2({\mathrm{SO}}_4{)}_3$ is electrolyzed for 'x' min with a current of 1.5 A to deposit 0.3482 g of Fe.

The value of $x$ is ______. [nearest integer]
Given: $1\mathrm{F}=96500\mathrm{C}{\mathrm{mol}}^{-1}$
Atomic mass of …

In a cell, the following reactions take place
${\mathrm{Fe}}^{2+}\to {\mathrm{Fe}}^{3+}{\mathrm{e}}^{-}$

$2{\mathrm{I}}^{-}\to {\mathrm{I}}_2+2{\mathrm{e}}^{-}$ …

The electrode potential of $M^{2+}/M$ of $3d-$ series elements shows positive value for:

The reaction of sulphur in alkaline medium is given below:
${\mathrm{S}}_{8(\mathrm{s})}+a{\mathrm{OH}}_{(\mathrm{aq})}^{-}⟶b{\mathrm{S}}_{(\mathrm{aq})}^{2-}+c{\mathrm{S}}_2{\mathrm{O}}_{3(\mathrm{aq})}^{2-}+d{\mathrm{H}}_2{\mathrm{O}}_{(\ell )}$
The value of 'a' is ____ …

Given below are two statements:
Statement I : The limiting molar conductivity of KCl (strong electrolyte) is higher compared to that of ${\mathrm{CH}}_3\mathrm{COOH}$ (weak electrolyte).
Statement II: Molar conductivity decreases with decrease in concentration of electrolyte.
In …

These are physical properties of an element
(A) Sublimation enthalpy
(B) Ionisation enthalpy
(C) Hydration enthalpy
(D) Electron gain enthalpy

The total number of above properties that affect the reduction potential is ______ (Integer answer)

For the galvanic cell,
$\mathrm{Zn}(\mathrm{s})+{\mathrm{Cu}}^{2+}(0.02\mathrm{M})\to {\mathrm{Zn}}^{2+}(0.04\mathrm{M})+\mathrm{Cu}(\mathrm{s})$,
${\mathrm{E}}_{\text{cell }}=$ $\_\_\_\_$ $\times 10^{-2}\mathrm{V}$.
(Nearest integer)
[Use: …

The magnitude of the change in oxidising power of the ${\mathrm{MnO}}_4^{-}/{\mathrm{Mn}}^{2+}$ couple is $\mathrm{x}\times 10^{-4}\mathrm{V}$, if the ${\mathrm{H}}^{+}$ concentration is decreased from 1 M to $10^{-4}\mathrm{M}$ at $25^{\circ }\mathrm{C}$ (Assume concentration o …

Potassium chlorate is prepared by electrolysis of KCl in basic solution as shown by following equation.
$6{\mathrm{OH}}^{-}+{\mathrm{Cl}}^{-}\to {\mathrm{ClO}}_3^{-}+3{\mathrm{H}}_2\mathrm{O}+6{\mathrm{e}}^{-}$
A current of xA has to be passed for 10 h to produce 10.0 g …

The resistance of a conductivity cell with cell constant $1.14{\mathrm{cm}}^{-1}$, containing 0.001 M KCl at 298 K is $1500\Omega$. The molar conductivity of 0.001 M KCl solution at 298 K in $\mathrm{S}{\mathrm{cm}}^2{\mathrm{mol}}^{-1}$ is ____. (Integer answer)

In basic medium ${\mathrm{CrO}}_4{}^{2-}$ oxidises ${\mathrm{S}}_2{\mathrm{O}}_3{}^{2-}$ to form ${\mathrm{SO}}_4{}^{2-}$ and itself changes into $\mathrm{Cr}(\mathrm{OH}{)}_4{}^{-}$.
The volume of $0.154\mathrm{M}{\mathrm{CrO}}_4{}^{2-}$ required to react with …

Assume a cell with the following reaction


$E_{\text{cell}}$ for the above reaction is ______ V. (Nearest integer)
[Given: $\log 2.5=0.3979$, $T=298\text{ K}$]

Consider the following reaction
${\mathrm{MnO}}_4^{-}+8{\mathrm{H}}^{+}+5{\mathrm{e}}^{-}\to {\mathrm{Mn}}^{+2}+4{\mathrm{H}}_2\mathrm{O},{\mathrm{E}}^{\circ }=1.51\mathrm{V}$.
The quantity of electricity required in Faraday to reduce five moles of ${\mathrm{MnO}}_4^{-}$is …

When 10 mL of an aqueous solution of $\mathrm{KMnO}{}_4$ was titrated in acidic medium, equal volume of 0.1 M of an aqueous solution of ferrous sulphate was required for complete discharge of colour. The strength of $\mathrm{KMnO}{}_4$ in grams per litre is ______ $\times 10^{-2}$. (Nearest in …

In mildly alkaline medium, thiosulphate ion is oxidized by ${\mathrm{MnO}}_4^{-}$ to "A". The oxidation state of sulphur in 'A' is ____

Emf of the following cell at 298 K in V is $x\times 10^{-2}$.

The value of $x$ is ____ (Rounded off to the nearest integer)
[Given: …

Match List-I with List-II.

List - I (Parameter)
(a) Cell constant
(b) Molar conductivity
(c) Conductivity
(d) Degree of dissociation of electrolyte

List - II (Unit)
(i) S cm² mol⁻¹
(ii) Dimensionless
(iii) m⁻¹
(iv) Ω⁻¹ m⁻¹

Choose the most appropriate answer from the options gi …

In which one of the following sets all species show disproportionation reaction ?

Consider the following cell reaction :
${\mathrm{Cd}}_{(\mathrm{s})}+{\mathrm{Hg}}_2{\mathrm{SO}}_{4(\mathrm{s})}+\frac{9}{5}{\mathrm{H}}_2{\mathrm{O}}_{(\mathrm{l})}+{\mathrm{CdSO}}_4\cdot \frac{9}{5}{\mathrm{H}}_2{\mathrm{O}}_{(\mathrm{s})}+2{\mathrm{Hg}}_{(\mathrm{l})}$
The valu …

The oxidation states of 'P' in ${\mathrm{H}}_4{\mathrm{P}}_2{\mathrm{O}}_7$, ${\mathrm{H}}_4{\mathrm{P}}_2{\mathrm{O}}_5$ and ${\mathrm{H}}_4{\mathrm{P}}_2{\mathrm{O}}_6$, respectively are:

The conductivity of a weak acid HA of concentration $0.001\mathrm{mol}{\mathrm{L}}^{-1}$ is $2.0\times 10^{-5}\mathrm{S}{\mathrm{cm}}^{-1}$. If ${\wedge }_{\mathrm{m}}^{\circ }(\mathrm{HA})=190\mathrm{S}{\mathrm{cm}}^2{\mathrm{mol}}^{-1}$, the ionization constant ( …

The correct order of conductivity of ions in water is:

15 mL of aqueous solution of ${\mathrm{Fe}}^{2+}$ in acidic medium completely reacted with 20 mL of 0.03 M aqueous ${\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}$. The molarity of the ${\mathrm{Fe}}^{2+}$ solution is ______ $\times 10^{-2}$ M
(Round off to the nearest integer).

When 10 ml of an aqueous solution of ${\mathrm{Fe}}^{2+}$ ions was titrated in the presence of dil ${\mathrm{H}}_2{\mathrm{SO}}_4$ using diphenylamine indicator, 15 mL of 0.02 M solution of ${\mathrm{K}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7$ was required to get the end point. Th …

Consider the cell at $25^{\circ }\mathrm{C}$
$\mathrm{Zn}\left|{\mathrm{Zn}}^{2+}(\mathrm{aq}),(1\mathrm{M})\right|\left|{\mathrm{Fe}}^{3+}(\mathrm{aq}),{\mathrm{Fe}}^{2+}(\mathrm{aq})\right|\mathrm{Pt}(\mathrm{s})$
The fraction of total iron present as ${\mathrm{Fe}}^{3+}$ ion …

Identify the process in which change in the oxidation state is five:

For the cell $\mathrm{Cu}(\mathrm{s})\left|{\mathrm{Cu}}^{2+}(\mathrm{aq})(0.1\mathrm{M})\right|\left|{\mathrm{Ag}}^{+}(\mathrm{aq})(0.01\mathrm{M})\right|\mathrm{Ag}(\mathrm{s})$
The cell potential ${\mathrm{E}}_1=0.3095\mathrm{V}$
For the cell …

10.0 ml of $0.05\mathrm{M}{\mathrm{KMnO}}_4$ solution was consumed in a titration with 10.0 mL of given oxalic acid dehydrate solution. The strength of given oxalic acid solution is ____ $\times 10^{-2}\mathrm{g}/\mathrm{L}$ (Round off to the Nearest Integer).

If the conductivity of mercury at $0^{\circ }\mathrm{C}$ is $1.07\times 10^6\mathrm{S}{\mathrm{m}}^{-1}$ and the resistance of a cell containing mercury is $0.243\Omega$, then the cell constant of the cell is $\times \times 10^4{\mathrm{m}}^{-1}$. The value of $\times$ is …

2MnO₄⁻ + bC₂O₄²⁻ + cH⁺ → xMn²⁺ + yCO₂ + zH₂O
If the above equation is balanced with integer coefficients, the value of c is ____.
(Round off to the nearest Integer).

A $5.0\mathrm{mmol}{\mathrm{dm}}^{-3}$ aqueous solution of KCl has a conductance of 0.55 mS when measured in a cell of cell constant $1.3{\mathrm{cm}}^{-1}$. The molar conductivity of this solution is _____ ${\mathrm{mSm}}^2{\mathrm{mol}}^{-1}$. (Round off to the nearest integer) …

The molar conductivities at infinite dilution of barium chloride, sulphuric acid and hydrochloric acid are 280, 860 and $426{\mathrm{Scm}}^2{\mathrm{mol}}^{-1}$ respectively. The molar conductivity at infinite dilution of barium sulphate is ______ …

A KCl solution of conductivity $0.14{\mathrm{Sm}}^{-1}$ shows a resistance of $4.19\Omega$ in a conductivity cell. If the same cell is filled with an HCl solution, the resistance drops to $1.03\Omega$. The conductivity of the HCl solution is ______ …

For the reaction
$2{\mathrm{Fe}}^{3+}(\mathrm{aq})+2{\mathrm{I}}^{-}(\mathrm{aq})\to 2{\mathrm{Fe}}^{2+}(\mathrm{aq})+{\mathrm{I}}_2(\mathrm{s})$
The magnitude of the standard molar free energy change,
${\Delta }_{\mathrm{r}}{\mathrm{G}}_{\mathrm{m}}^{\mathrm{o}}=-$ ___ …

The oxidation states of nitrogen in NO, NO₂, N₂O and NO₃⁻ are in the order of:

Oxidation number of potassium in ${\mathrm{K}}_2\mathrm{O}$, ${\mathrm{K}}_2{\mathrm{O}}_2$ and ${\mathrm{KO}}_2$ respectively is

Given that the standard potential (${\mathrm{E}}^{\circ }$) of ${\mathrm{Cu}}^{2+}/\mathrm{Cu}$ and ${\mathrm{Cu}}^{+}/\mathrm{Cu}$ are 0.34 V and 0.522 V respectively, the ${\mathrm{E}}^{\circ }$ of ${\mathrm{Cu}}^{2+}/{\mathrm{Cu}}^{+}$ is

The redox reaction among the following is