Electrochemistry · Chemistry · JEE Main

Consider the following half cell reaction

$$ \text{Cr}_2\text{O}_7^{2-} \, (\text{aq}) + 6\text{e}^- + 14\text{H}^+ \, (\text{aq}) \rightarrow 2\text{Cr}^{3+} \, (\text{aq}) + 7\text{H}_2\text{O} \, (\ell) $$

The reaction was conducted with the ratio of $$\frac{[\text{Cr}^{3+}]^2}{[\text{Cr}_2\text{O}_7^{2-}]} = 10^{-6}$$. The pH value at which the EMF of the half cell will become zero is __________.

(nearest integer value)

[Given: standard half cell reduction potential $$E^{\circ}_{\text{Cr}_2\text{O}_7^{2-}, \text{H}^+/\text{Cr}^{3+}} = 1.33\, \text{V}$$, $$\frac{2.303RT}{F} = 0.059\, \text{V}$$.]

1 Faraday electricity was passed through $\mathrm{Cu}^{2+}(1.5 \mathrm{M}, 1 \mathrm{~L}) / \mathrm{Cu}$ and 0.1 Faraday was passed through $\mathrm{Ag}^{+}(0.2 \mathrm{M}, 1 \mathrm{~L}) / \mathrm{Ag}$ electrolytic cells. After this the two cells were connected as shown below to make an electrochemical cell. The emf of the cell thus formed at 298 K is __________ mV (nearest integer)

$$\begin{aligned} \text { Given : } \mathrm{E}^{\circ} \mathrm{Cu}^{2+} / \mathrm{Cu} & =0.34 \mathrm{~V} \\\\ \mathrm{E}^{\circ} \mathrm{Ag}^{+} / \mathrm{Ag} & =0.8 \mathrm{~V} \\\\ \frac{2 \cdot 303 \mathrm{RT}}{\mathrm{~F}} & =0.06 \mathrm{~V} \end{aligned}$$

$0.2 \%(\mathrm{w} / \mathrm{v})$ solution of NaOH is measured to have resistivity $870.0 \mathrm{~m} \Omega \mathrm{~m}$. The molar conductivity of the solution will be__________$\times 10^2 \mathrm{mS} \mathrm{dm}^2 \mathrm{~mol}^{-1}$. (Nearest integer)

Consider the following electrochemical cell at standard condition.

$$\mathrm{Au}(\mathrm{~s})\left|\mathrm{QH}_2, \mathrm{Q}\right| \mathrm{NH}_4 \mathrm{X}(0.01 \mathrm{M})| | \mathrm{Ag}^{+}(1 \mathrm{M}) \mid \mathrm{Ag}(\mathrm{~s}) \mathrm{E}_{\text {cell }}=+0.4 \mathrm{~V}$$

The couple $\mathrm{QH}_2 / \mathrm{Q}$ represents quinhydrone electrode, the half cell reaction is given below:

$$\left[\text { Given : } \mathrm{E}_{\mathrm{Ag}^{+} / \mathrm{Ag}}^0=+0.8 \mathrm{~V} \text { and } \frac{2.303 \mathrm{RT}}{\mathrm{~F}}=0.06 \mathrm{~V}\right]$$

The $\mathrm{pK}_{\mathrm{b}}$ value of the ammonium halide salt $\left(\mathrm{NH}_4 \mathrm{X}\right)$ used here is __________ . (nearest integer)

Given below is the plot of the molar conductivity vs $\sqrt{\text { concentration }}$ for KCl in aqueous solution.

If, for the higher concentration of KCl solution, the resistance of the conductivity cell is $100 \Omega$, then the resistance of the same cell with the dilute solution is ' x ' $\Omega$

The value of $x$ is _________ (Nearest integer)

The standard reduction potentials at $$298 \mathrm{~K}$$ for the following half cells are given below :

$$\mathrm{Cr}_2 \mathrm{O}_7^{2-}+14 \mathrm{H}^{+}+6 \mathrm{e}^{-} \rightarrow 2 \mathrm{Cr}^{3+}+7 \mathrm{H}_2 \mathrm{O}, \quad \mathrm{E}^{\circ}=1.33 \mathrm{~V}$$

$$\begin{array}{ll} \mathrm{Fe}^{3+}(\mathrm{aq})+3 \mathrm{e}^{-} \rightarrow \mathrm{Fe} & \mathrm{E}^{\circ}=-0.04 \mathrm{~V} \\ \mathrm{Ni}^{2+}(\mathrm{aq})+2 \mathrm{e}^{-} \rightarrow \mathrm{Ni} & \mathrm{E}^{\circ}=-0.25 \mathrm{~V} \\ \mathrm{Ag}^{+}(\mathrm{aq})+\mathrm{e}^{-} \rightarrow \mathrm{Ag} & \mathrm{E}^{\circ}=0.80 \mathrm{~V} \\ \mathrm{Au}^{3+}(\mathrm{aq})+3 \mathrm{e}^{-} \rightarrow \mathrm{Au} & \mathrm{E}^{\circ}=1.40 \mathrm{~V} \end{array}$$

Consider the given electrochemical reactions,

The number of metal(s) which will be oxidized be $$\mathrm{Cr}_2 \mathrm{O}_7^{2-}$$, in aqueous solution is _________.

Number of alkanes obtained on electrolysis of a mixture of $$\mathrm{CH}_3 \mathrm{COONa}$$ and $$\mathrm{C}_2 \mathrm{H}_5 \mathrm{COONa}$$ is ________.

One Faraday of electricity liberates $$x \times 10^{-1}$$ gram atom of copper from copper sulphate. $$x$$ is ________.

A constant current was passed through a solution of $$\mathrm{AuCl}_4^{-}$$ ion between gold electrodes. After a period of 10.0 minutes, the increase in mass of cathode was $$1.314 \mathrm{~g}$$. The total charge passed through the solution is _______ $$\times 10^{-2} \mathrm{~F}$$.

(Given atomic mass of $$\mathrm{Au}=197$$)

The mass of zinc produced by the electrolysis of zine sulphate solution with a steady current of $$0.015 \mathrm{~A}$$ for 15 minutes is _________ $$\times 10^{-4} \mathrm{~g}$$.

(Atomic mass of zinc $$=65.4 \mathrm{~amu}$$)

The hydrogen electrode is dipped in a solution of $$\mathrm{pH}=3$$ at $$25^{\circ} \mathrm{C}$$. The potential of the electrode will be _________ $$\times 10^{-2} \mathrm{~V}$$.

$$\left(\frac{2.303 \mathrm{RT}}{\mathrm{F}}=0.059 \mathrm{~V}\right)$$

The mass of silver (Molar mass of $$\mathrm{Ag}: 108 \mathrm{~gmol}^{-1}$$ ) displaced by a quantity of electricity which displaces $$5600 \mathrm{~mL}$$ of $$\mathrm{O}_2$$ at S.T.P. will be ______ g.

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

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

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

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

A metal surface of $$100 \mathrm{~cm}^{2}$$ area has to be coated with nickel layer of thickness $$0.001 \mathrm{~mm}$$. A current of $$2 \mathrm{~A}$$ was passed through a solution of $$\mathrm{Ni}\left(\mathrm{NO}_{3}\right)_{2}$$ for '$$\mathrm{x}$$' seconds to coat the desired layer. The value of $$\mathrm{x}$$ is __________. (Nearest integer) ( $$\rho_{\mathrm{Ni}}$$ (density of Nickel) is $$10 \mathrm{~g} \mathrm{~mL}$$, Molar mass of Nickel is $$60 \mathrm{~g} \mathrm{~mol}^{-1}$$ $$\left.\mathrm{F}=96500 ~\mathrm{C} ~\mathrm{mol}^{-1}\right)$$

The number of correct statements from the following is __________

A. $$\mathrm{E_{\text {cell }}}$$ is an intensive parameter

B. A negative $$\mathrm{E}^{\ominus}$$ means that the redox couple is a stronger reducing agent than the $$\mathrm{H}^{+} / \mathrm{H}_{2}$$ couple.

C. The amount of electricity required for oxidation or reduction depends on the stoichiometry of the electrode reaction.

D. The amount of chemical reaction which occurs at any electrode during electrolysis by a current is proportional to the quantity of electricity passed through the electrolyte.

In an electrochemical reaction of lead, at standard temperature, if $$\mathrm{E}^{0}\left(\mathrm{~Pb}^{2+} / \mathrm{Pb}\right)=\mathrm{m}$$ Volt and $$\mathrm{E}^{0}\left(\mathrm{~Pb}^{4+} / \mathrm{Pb}\right)=\mathrm{n}$$ Volt, then the value of $$\mathrm{E}^{0}\left(\mathrm{~Pb}^{2+} / \mathrm{Pb}^{4+}\right)$$ is given by $$\mathrm{m-x n}$$. The value of $$\mathrm{x}$$ is ___________. (Nearest integer)

The specific conductance of $$0.0025 ~\mathrm{M}$$ acetic acid is $$5 \times 10^{-5} \mathrm{~S} \mathrm{~cm}^{-1}$$ at a certain temperature. The dissociation constant of acetic acid is __________ $$\times ~10^{-7}$$ (Nearest integer)

Consider limiting molar conductivity of $$\mathrm{CH}_{3} \mathrm{COOH}$$ as $$400 \mathrm{~S} \mathrm{~cm}^{2} \mathrm{~mol}^{-1}$$

$$\mathrm{FeO_4^{2 - }\buildrel { + 2.2V} \over \longrightarrow F{e^{3 + }}\buildrel { + 0.70V} \over \longrightarrow F{e^{2 + }}\buildrel { - 0.45V} \over \longrightarrow F{e^0}}$$

$$E_{FeO_4^{2 - }/F{e^{2 + }}}^\theta $$ is $$x \times {10^{ - 3}}$$ V. The value of $$x$$ is _________

The number of incorrect statements from the following is ___________.

A. The electrical work that a reaction can perform at constant pressure and temperature is equal to the reaction Gibbs energy.

B. $$\mathrm{E_{cell}^{\circ}}$$ cell is dependent on the pressure.

C. $$\frac{d E^{\theta} \text { cell }}{\mathrm{dT}}=\frac{\Delta_{\mathrm{r}} \mathrm{S}^{\theta}}{\mathrm{nF}}$$

D. A cell is operating reversibly if the cell potential is exactly balanced by an opposing source of potential difference.

The standard reduction potentials at $$298 \mathrm{~K}$$ for the following half cells are given below:

$$\mathrm{NO}_{3}^{-}+4 \mathrm{H}^{+}+3 \mathrm{e}^{-} \rightarrow \mathrm{NO}(\mathrm{g})+2 \mathrm{H}_{2} \mathrm{O} \quad \mathrm{E}^{\theta}=0.97 \mathrm{~V}$$

$$\mathrm{V}^{2+}(\mathrm{aq})+2 \mathrm{e}^{-} \rightarrow \mathrm{V} \quad\quad\quad \mathrm{E}^{\theta}=-1.19 \mathrm{~V}$$

$$\mathrm{Fe}^{3+}(\mathrm{aq})+3 \mathrm{e}^{-} \rightarrow \mathrm{Fe} \quad\quad\quad \mathrm{E}^{\theta}=-0.04 \mathrm{~V}$$

$$\mathrm{Ag}^{+}(\mathrm{aq})+\mathrm{e}^{-} \rightarrow \mathrm{Ag}(\mathrm{s}) \quad\quad\quad \mathrm{E}^{\theta}=0.80 \mathrm{~V}$$

$$\mathrm{Au}^{3+}(\mathrm{aq})+3 \mathrm{e}^{-} \rightarrow \mathrm{Au}(\mathrm{s}) \quad\quad\quad \mathrm{E}^{\theta}=1.40 \mathrm{~V}$$

The number of metal(s) which will be oxidized by $$\mathrm{NO}_{3}^{-}$$ in aqueous solution is __________.

$$1 \times 10^{-5} ~\mathrm{M} ~\mathrm{AgNO}_{3}$$ is added to $$1 \mathrm{~L}$$ of saturated solution of $$\mathrm{AgBr}$$. The conductivity of this solution at $$298 \mathrm{~K}$$ is _____________ $$\times 10^{-8} \mathrm{~S} \mathrm{~m}^{-1}$$.

[Given : $$\mathrm{K}_{\mathrm{SP}}(\mathrm{AgBr})=4.9 \times 10^{-13}$$ at $$298 \mathrm{~K}$$

$$ \begin{aligned} & \lambda_{\mathrm{Ag}^{+}}^{0}=6 \times 10^{-3} \mathrm{~S} \mathrm{~m}^{2} \mathrm{~mol}^{-1} \\ & \lambda_{\mathrm{Br}^{-}}^{0}=8 \times 10^{-3} \mathrm{~S} \mathrm{~m}^{2} \mathrm{~mol}^{-1} \\ & \left.\lambda_{\mathrm{NO}_{3}^{-}}^{0}=7 \times 10^{-3} \mathrm{~S} \mathrm{~m}^{2} \mathrm{~mol}^{-1}\right] \end{aligned} $$

At what pH, given half cell $$\mathrm{MnO_{4}^{-}(0.1~M)~|~Mn^{2+}(0.001~M)}$$ will have electrode potential of 1.282 V? ___________ (Nearest Integer)

Given $$\mathrm{E_{MnO_4^ - |M{n^{2 + }}}^o}=1.54~\mathrm{V},\frac{2.303\mathrm{RT}}{\mathrm{F}}=0.059\mathrm{V}$$

The logarithm of equilibrium constant for the reaction $$\mathrm{Pd}^{2+}+4 \mathrm{Cl}^{-} \rightleftharpoons \mathrm{PdCl}_{4}^{2-}$$ is ___________ (Nearest integer)

Given : $$\frac{2.303 R \mathrm{~T}}{\mathrm{~F}}=0.06 \mathrm{~V}$$

$$ \mathrm{Pd}_{(\mathrm{aq})}^{2+}+2 \mathrm{e}^{-} \rightleftharpoons \mathrm{Pd}(\mathrm{s}) \quad \mathrm{E}^{\ominus}=0.83 \mathrm{~V} $$

$$ \begin{aligned} & \mathrm{PdCl}_{4}^{2-}(\mathrm{aq})+2 \mathrm{e}^{-} \rightleftharpoons \mathrm{Pd}(\mathrm{s})+4 \mathrm{Cl}^{-}(\mathrm{aq}) \mathrm{E}^{\ominus}=0.65 \mathrm{~V} \end{aligned} $$

Consider the cell

$$\mathrm{Pt}_{(\mathrm{s})}\left|\mathrm{H}_{2}(\mathrm{~g}, 1 \mathrm{~atm})\right| \mathrm{H}^{+}(\mathrm{aq}, 1 \mathrm{M})|| \mathrm{Fe}^{3+}(\mathrm{aq}), \mathrm{Fe}^{2+}(\mathrm{aq}) \mid \operatorname{Pt}(\mathrm{s})$$

When the potential of the cell is $$0.712 \mathrm{~V}$$ at $$298 \mathrm{~K}$$, the ratio $$\left[\mathrm{Fe}^{2+}\right] /\left[\mathrm{Fe}^{3+}\right]$$ is _____________. (Nearest integer)

Given : $$\mathrm{Fe}^{3+}+\mathrm{e}^{-}=\mathrm{Fe}^{2+}, \mathrm{E}^{\theta} \mathrm{Fe}^{3+}, \mathrm{Fe}^{2+} \mid \mathrm{Pt}=0.771$$

$$ \frac{2.303 \mathrm{RT}}{\mathrm{F}}=0.06 \mathrm{~V} $$

The equilibrium constant for the reaction

$$\mathrm{Zn(s)+Sn^{2+}(aq)}$$ $$\rightleftharpoons$$ $$\mathrm{Zn^{2+}(aq)+Sn(s)}$$ is $$1\times10^{20}$$ at 298 K. The magnitude of standard electrode potential of $$\mathrm{Sn/Sn^{2+}}$$ if $$\mathrm{E_{Z{n^{2 + }}/Zn}^\Theta = - 0.76~V}$$ is __________ $$\times 10^{-2}$$ V. (Nearest integer)

Given : $$\mathrm{\frac{2.303RT}{F}=0.059~V}$$

Following figure shows dependence of molar conductance of two electrolytes on concentration. $$\Lambda \mathop m\limits^o $$ is the limiting molar conductivity.

The number of $$\mathrm{\underline {incorrect} }$$ statement(s) from the following is ___________

(A) $$\Lambda \mathop m\limits^o $$ for electrolyte A is obtained by extrapolation

(B) For electrolyte B, $$\Lambda \mathop m\limits $$ vs $$\sqrt c$$ graph is a straight line with intercept equal to $$\Lambda \mathop m\limits^o $$

(C) At infinite dilution, the value of degree of dissociation approaches zero for electrolyte B.

(D) $$\Lambda \mathop m\limits^o $$ for any electrolyte A and B can be calculated using $$\lambda^\circ$$ for individual ions

$$Pt(s)|{H_2}(g)(1\,bar)|{H^ + }(aq)(1\,M)||{M^{3 + }}(aq),{M^ + }(aq)|Pt(s)$$

The $$\mathrm{E_{cell}}$$ for the given cell is 0.1115 V at 298 K when $${{\left[ {{M^ + }(aq)} \right]} \over {\left[ {{M^{3 + }}(aq)} \right]}} = {10^a}$$

The value of $$a$$ is ____________

Given : $$\mathrm{E_{{M^{3 + }}/{M^ + }}^\theta = 0.2}$$ V

$${{2.303RT} \over F} = 0.059V$$

Consider the cell

$$\mathrm{Pt(s)|{H_2}(g)\,(1\,atm)|{H^ + }\,(aq,[{H^ + }] = 1)||F{e^{3 + }}(aq),F{e^{2 + }}(aq)|Pt(s)}$$

Given $$\mathrm{E_{F{e^{3 + }}/F{e^{2 + }}}^o = 0.771\,V}$$ and $$\mathrm{E_{{H^ + }/1/2\,{H_2}}^o = 0\,V,\,T = 298\,K}$$

If the potential of the cell is 0.712 V, the ratio of concentration of Fe$$^{2+}$$ to Fe$$^{3+}$$ is _____________ (Nearest integer)

At 298 K, a 1 litre solution containing 10 mmol of $$\mathrm{C{r_2}O_7^{2 - }}$$ and 100 mmol of $$\mathrm{Cr^{3+}}$$ shows a pH of 3.0.

Given : $$\mathrm{C{r_2}O_7^{2 - } \to C{r^{3 + }}\,;\,E^\circ = 1.330}$$V

and $$\mathrm{{{2.303\,RT} \over F} = 0.059}$$ V

The potential for the half cell reaction is $$x\times10^{-3}$$ V. The value of $$x$$ is __________

For a cell, $$\mathrm{Cu}(\mathrm{s})\left|\mathrm{Cu}^{2+}(0.001 \,\mathrm{M}) \| \mathrm{Ag}^{+}(0.01 \,\mathrm{M})\right| \mathrm{Ag}(\mathrm{s})$$

the cell potential is found to be $$0.43 \mathrm{~V}$$ at $$298 \mathrm{~K}$$. The magnitude of standard electrode potential for $$\mathrm{Cu}^{2+} / \mathrm{Cu}$$ is _________ $$\times 10^{-2} \mathrm{~V}$$.

[Given : $$E_{A{g^ + }/Ag}^\Theta $$ = 0.80 V and $${{2.303RT} \over F}$$ = 0.06 V]

Resistance of a conductivity cell (cell constant $$129 \mathrm{~m}^{-1}$$) filled with $$74.5 \,\mathrm{ppm}$$ solution of $$\mathrm{KCl}$$ is $$100 \,\Omega$$ (labelled as solution 1). When the same cell is filled with $$\mathrm{KCl}$$ solution of $$149 \,\mathrm{ppm}$$, the resistance is $$50 \,\Omega$$ (labelled as solution 2). The ratio of molar conductivity of solution 1 and solution 2 is i.e. $$\frac{\wedge_{1}}{\wedge_{2}}=x \times 10^{-3}$$. The value of $$x$$ is __________. (Nearest integer)

Given, molar mass of $$\mathrm{KCl}$$ is $$74.5 \mathrm{~g} \mathrm{~mol}^{-1}$$.

The amount of charge in $$\mathrm{F}$$ (Faraday) required to obtain one mole of iron from $$\mathrm{Fe}_{3} \mathrm{O}_{4}$$ is ___________. (Nearest Integer)

The spin-only magnetic moment value of M³⁺ ion (in gaseous state) from the pairs Cr³⁺ / Cr²⁺, Mn³⁺ / Mn²⁺, Fe³⁺ / Fe²⁺ and Co³⁺ / Co²⁺ that has negative standard electrode potential, is ____________ B.M. [Nearest integer]

The cell potential for $$\mathrm{Zn}\left|\mathrm{Zn}^{2+}(\mathrm{aq})\right|\left|\mathrm{Sn}^{x+}\right| \mathrm{Sn}$$ is $$0.801 \mathrm{~V}$$ at $$298 \mathrm{~K}$$. The reaction quotient for the above reaction is $$10^{-2}$$. The number of electrons involved in the given electrochemical cell reaction is ____________.

$$\left(\right.$$ Given $$: \mathrm{E}_{\mathrm{Zn}^{2+} \mid \mathrm{Zn}}^{\mathrm{o}}=-0.763 \mathrm{~V}, \mathrm{E}_{\mathrm{Sn}^{x+} \mid \mathrm{Sn}}^{\mathrm{o}}=+0.008 \mathrm{~V}$$ and $$\left.\frac{2.303 \mathrm{RT}}{\mathrm{F}}=0.06 \mathrm{~V}\right)$$

The cell potential for the given cell at 298 K

Pt| H₂ (g, 1 bar) | H⁺ (aq) || Cu²⁺ (aq) | Cu(s)

is 0.31 V. The pH of the acidic solution is found to be 3, whereas the concentration of Cu²⁺ is 10^$$-$$x M. The value of x is ___________.

(Given : $$E_{C{u^{2 + }}/Cu}^\Theta $$ = 0.34 V and $${{2.303\,RT} \over F}$$ = 0.06 V)

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 a STP is _____________ cm³. (Nearest integer)

[Given : Faraday constant F = 96500 C mol^$$-$$1 at STP, molar volume of an ideal gas is 22.7 L mol^$$-$$1]

For the given reactions

Sn²⁺ + 2e^$$-$$ $$\to$$ Sn

Sn⁴⁺ + 4e^$$-$$ $$\to$$ Sn

the electrode potentials are ; $$E_{S{n^{2 + }}/Sn}^o = - 0.140$$ V and $$E_{S{n^{4 + }}/Sn}^o = + 0.010$$ V. The magnitude of standard electrode potential for $$S{n^{4 + }}/S{n^{2 + }}$$ i.e. $$E_{S{n^{4 + }}/S{n^{2 + }}}^o$$ is _____________ $$\times$$ 10^$$-$$2 V. (Nearest integer)

The quantity of electricity in Faraday needed to reduce 1 mol of Cr₂O$$_7^{2 - }$$ to Cr³⁺ is ____________.

For the reaction taking place in the cell :

Pt (s)| H₂ (g)|H⁺(aq) || Ag⁺(aq) |Ag (s)

E$$_{cell}^o$$ = + 0.5332 V.

The value of $$\Delta$$_fG$$^\circ$$ is ______________ kJ mol^$$-$$1. (in nearest integer)

The limiting molar conductivities of NaI, NaNO₃ and AgNO₃ are 12.7, 12.0 and 13.3 mS m² mol^$$-$$1, respectively (all at 25$$^\circ$$C). The limiting molar conductivity of AgI at this temperature is ____________ mS m² mol^$$-$$1.

Cu(s) + Sn²⁺ (0.001M) $$\to$$ Cu²⁺ (0.01M) + Sn(s)

The Gibbs free energy change for the above reaction at 298 K is x $$\times$$ 10^$$-$$1 kJ mol^$$-$$1. The value of x is __________. [nearest integer]

[Given : $$E_{C{u^{2 + }}/Cu}^\Theta = 0.34\,V$$ ; $$E_{S{n^{2 + }}/Sn}^\Theta = - 0.14\,V$$ ; F = 96500 C mol^$$-$$1]

A solution of Fe₂(SO₄)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 F = 96500 C mol^$$-$$1

Atomic mass of Fe = 56 g mol^$$-$$1

In a cell, the following reactions take place

$$\matrix{ {F{e^{2 + }} \to F{e^{3 + }} + {e^ - }} & {E_{F{e^{3 + }}/F{e^{2 + }}}^o = 0.77\,V} \cr {2{I^ - } \to {I_2} + 2{e^ - }} & {E_{{I_2}/{I^ - }}^o = 0.54\,V} \cr } $$

The standard electrode potential for the spontaneous reaction in the cell is x $$\times$$ 10^$$-$$2 V 298 K. The value of x is ____________. (Nearest Integer)

The resistance of a 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 S cm^$$-$$1, then the cell constant of the conductivity cell is ____________ $$\times$$ 10^$$-$$3 cm^$$-$$1.

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)

(Given : $$E_{C{u^{2 + }}/Cu}^o = 0.34$$ V and $${{2.303\,RT} \over F} = 0.06$$ V)

Given below are two statements :

1 M aqueous solutions of each of Cu(NO₃)₂, AgNO₃, Hg₂(NO₃)₂, Mg(NO₃)₂ are electrolysed using inert electrodes. Given: E⁰_Ag⁺/Ag = 0.80 V, E⁰_Hg2²⁺/Hg = 0.79 V, E⁰_Cu²⁺/Cu = 0.24 V and E⁰_Mg²⁺/Mg = -2.37 V.

Statement (I) : With increasing voltage, the sequence of deposition of metals on the cathode will be Ag, Hg and Cu.

Statement (II) : Magnesium will not be deposited at the cathode instead oxygen gas will be evolved at the cathode.

In the light of the above statements, choose the most appropriate answer from the options given below :

On charging the lead storage battery, the oxidation state of lead changes from $x_1$ to $y_1$ at the anode and from $x_2$ to $y_2$ at the cathode. The values of $x_1, y_1, x_2, y_2$ are respectively :

The standard cell potential $\left(\mathrm{E}_{\text {cell }}^{\ominus}\right)$ of a fuel cell based on the oxidation of methanol in air that has been used to power television relay station is measured as 1.21 V . The standard half cell reduction potential for $\mathrm{O}_2\left(\mathrm{E}_{\mathrm{O}_2 / \mathrm{H}_2 \mathrm{O}}^{\circ}\right)$ is 1.229 V .

Choose the correct statement :

Match List - I with List - II :

Choose the correct answer from the options given below :

$\mathrm{O}_2$ gas will be evolved as a product of electrolysis of :

(A) an aqueous solution of $\mathrm{AgNO}_3$ using silver electrodes.

(B) an aqueous solution of $\mathrm{AgNO}_3$ using platinum electrodes.

(C) a dilute solution of $\mathrm{H}_2 \mathrm{SO}_4$ using platinum electrodes.

(D) a high concentration solution of $\mathrm{H}_2 \mathrm{SO}_4$ using platinum electrodes.

Choose the correct answer from the options given below :

For a Mg | Mg²⁺ (aq) || Ag⁺ (aq) | Ag the correct Nernst Equation is :

The molar conductivity of a weak electrolyte when plotted against the square root of its concentration, which of the following is expected to be observed?

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

Based on the data given below :

$$\begin{array}{ll} \mathrm{E}_{\mathrm{Cr}_2 \mathrm{O}_7^{2-} / \mathrm{Cr}^{3+}}^{\circ}=1.33 \mathrm{~V} & \mathrm{E}_{\mathrm{Cl}_2 / \mathrm{Cl}^{(-)}}^{\circ}=1.36 \mathrm{~V} \\ \mathrm{E}_{\mathrm{MnO}_4^{-} / \mathrm{Mn}^{2+}}^0=1.51 \mathrm{~V} & \mathrm{E}_{\mathrm{Cr}^{3+} / \mathrm{Cr}}^{\circ}=-0.74 \mathrm{~V} \end{array}$$

the strongest reducing agent is :

For the given cell

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

The standard cell potential of the above reaction is Given:

$$\begin{array}{lr} \mathrm{Ag}^{+}+\mathrm{e}^{-} \rightarrow \mathrm{Ag} & \mathrm{E}^\theta=\mathrm{xV} \\ \mathrm{Fe}^{2+}+2 \mathrm{e}^{-} \rightarrow \mathrm{Fe} & \mathrm{E}^\theta=\mathrm{yV} \\ \mathrm{Fe}^{3+}+3 \mathrm{e}^{-} \rightarrow \mathrm{Fe} & \mathrm{E}^\theta=\mathrm{zV} \end{array}$$

Standard electrode potentials for a few half cells are mentioned below :

$$\begin{aligned} & \mathrm{E}_{\mathrm{Cu}^{2+} / \mathrm{Cu}}^{\circ}=0.34 \mathrm{~V}, \mathrm{E}_{\mathrm{Zn}^{2+} / \mathrm{Zn}}^{\circ}=-0.76 \mathrm{~V} \\ & \mathrm{E}_{\mathrm{Ag}^{+} / \mathrm{Ag}}^{\circ}=0.80 \mathrm{~V}, \mathrm{E}_{\mathrm{Mg}^{2+} / \mathrm{Mg}}^{\circ}=-2.37 \mathrm{~V} \end{aligned}$$

Which one of the following cells gives the most negative value of $\Delta \mathrm{G}^{\circ}$ ?

$$ \mathrm{FeO}_4^{2-} \xrightarrow{+2.0 \mathrm{~V}} \mathrm{Fe}^{3+} \xrightarrow{0.8 \mathrm{~V}} \mathrm{Fe}^{2+} \xrightarrow{-0.5 \mathrm{~V}} \mathrm{Fe}^0 $$

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 :

Given below are two statements :

Statement (I) : Corrosion is an electrochemical phenomenon in which pure metal acts as an anode and impure metal as a cathode.

Statement (II) : The rate of corrosion is more in alkaline medium than in acidic medium.

In the light of the above statements, choose the correct answer from the options given below :

Which of the following electrolyte can be used to obtain $\mathrm{H}_2 \mathrm{~S}_2 \mathrm{O}_8$ by the process of electrolysis ?

A solution of aluminium chloride is electrolysed for 30 minutes using a current of 2 A . The amount of the aluminium deposited at the cathode is __________ .

[Given : molar mass of aluminium and chlorine are $27 \mathrm{~g} \mathrm{~mol}^{-1}$ and $35.5 \mathrm{~g} \mathrm{~mol}^{-1}$ respectively. Faraday constant $\left.=96500 \mathrm{C} \mathrm{~mol}^{-1}\right]$

Match List I with List II

Choose the correct answer from the options given below :

Which out of the following is a correct equation to show change in molar conductivity with respect to concentration for a weak electrolyte, if the symbols carry their usual meaning :

The molar conductivity for electrolytes $$A$$ and $$B$$ are plotted against $$C^{3 / 2}$$ as shown below. Electrolytes $$A$$ and $$B$$ respectively are:

The emf of cell $$\mathrm{Tl}\left|\underset{(0.001 \mathrm{M})}{\mathrm{Tl}^{+}}\right| \underset{(0.01 \mathrm{M})}{\mathrm{Cu}^{2+}} \mid \mathrm{Cu}$$ is $$0.83 \mathrm{~V}$$ at $$298 \mathrm{~K}$$. It could be increased by :

The reaction;

$$\frac{1}{2} \mathrm{H}_{2(\mathrm{~g})}+\mathrm{AgCl}_{(\mathrm{s})} \rightarrow \mathrm{H}_{(\mathrm{aq})}^{+}+\mathrm{Cl}_{(\mathrm{aq})}^{-}+\mathrm{Ag}_{(\mathrm{s})}$$

occurs in which of the following galvanic cell :

Given below are two statements :

Statement (I) : Fusion of $$\mathrm{MnO}_2$$ with $$\mathrm{KOH}$$ and an oxidising agent gives dark green $$\mathrm{K}_2 \mathrm{MnO}_4$$.

Statement (II) : Manganate ion on electrolytic oxidation in alkaline medium gives permanganate ion.

In the light of the above statements, choose the correct answer from the options given below :

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

A conductivity cell with two electrodes (dark side) are half filled with infinitely dilute aqueous solution of a weak electrolyte. If volume is doubled by adding more water at constant temperature, the molar conductivity of the cell will -

The quantity of silver deposited when one coulomb charge is passed through $$\mathrm{AgNO}_3$$ solution :

For the electro chemical cell

$$\mathrm{M}\left|\mathrm{M}^{2+}\right||\mathrm{X}| \mathrm{X}^{2-}$$

If $$\mathrm{E}_{\left(\mathrm{M}^{2+} / \mathrm{M}\right)}^0=0.46 \mathrm{~V}$$ and $$\mathrm{E}_{\left(\mathrm{x} / \mathrm{x}^{2-}\right)}^0=0.34 \mathrm{~V}$$.

Which of the following is correct?

Molar ionic conductivities of divalent cation and anion are $$57 \mathrm{~S~cm}^2 \mathrm{~mol}^{-1}$$ and $$73 \mathrm{~S~cm}^2 \mathrm{~mol}^{-1}$$ respectively. The molar conductivity of solution of an electrolyte with the above cation and anion will be:

The reaction at cathode in the cells commonly used in clocks involves.

Fuel cell, using hydrogen and oxygen as fuels,

A. has been used in spaceship

B. has as efficiency of $$40 \%$$ to produce electricity

C. uses aluminum as catalysts

D. is eco-friendly

E. is actually a type of Galvanic cell only

Choose the correct answer from the options given below:

For a strong electrolyte, a plot of molar conductivity against (concentration) $${ }^{1 / 2}$$ is a straight line, with a negative slope, the correct unit for the slope is

One of the commonly used electrode is calomel electrode. Under which of the following categories, calomel electrode comes?

What pressure (bar) of $$\mathrm{H}_2$$ would be required to make emf of hydrogen electrode zero in pure water at $$25^{\circ} \mathrm{C}$$ ?

Identify the factor from the following that does not affect electrolytic conductance of a solution.

Alkaline oxidative fusion of $$\mathrm{MnO}_2$$ gives "A" which on electrolytic oxidation in alkaline solution produces B. A and B respectively are

Reduction potential of ions are given below:

$$\begin{array}{ccc} \mathrm{ClO}_4^{-} & \mathrm{IO}_4^{-} & \mathrm{BrO}_4^{-} \\ \mathrm{E}^{\circ}=1.19 \mathrm{~V} & \mathrm{E}^{\circ}=1.65 \mathrm{~V} & \mathrm{E}^{\circ}=1.74 \mathrm{~V} \end{array}$$

The correct order of their oxidising power is :

Which of the following statements is not correct about rusting of iron?

For lead storage battery pick the correct statements

A. During charging of battery, $$\mathrm{PbSO}_{4}$$ on anode is converted into $$\mathrm{PbO}_{2}$$

B. During charging of battery, $$\mathrm{PbSO}_{4}$$ on cathode is converted into $$\mathrm{PbO}_{2}$$

C. Lead storage battery consists of grid of lead packed with $$\mathrm{PbO}_{2}$$ as anode

D. Lead storage battery has $$\sim 38 \%$$ solution of sulphuric acid as an electrolyte

Choose the correct answer from the options given below:

The reaction

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

occurs in which of the given galvanic cell.

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

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R)

Assertion (A) : An aqueous solution of $$\mathrm{KOH}$$ when used for volumetric analysis, its concentration should be checked before the use.

Reason (R) : On aging, $$\mathrm{KOH}$$ solution absorbs atmospheric $$\mathrm{CO}_{2}$$.

In the light of the above statements, choose the correct answer from the options given below :

Which one of the following statements is correct for electrolysis of brine solution?

The standard electrode potential $$\mathrm{(M^{3+}/M^{2+})}$$ for V, Cr, Mn & 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 :

Choose the correct representation of conductometric titration of benzoic acid vs sodium hydroxide.

Match List - I with List - II.

Choose the correct answer from the options given below:

Given below are two statements :

Statement I : For KI, molar conductivity increases steeply with dilution

Statement II : For carbonic acid, molar conductivity increases slowly with dilution

In the light of the above statements, choose the correct answer from the options given below :

The molar conductivity of a conductivity cell filled with 10 moles of 20 mL NaCl solution is $${\Lambda _{m1}}$$ and that of 20 moles another identical cell heaving 80 mL NaCl solution is $${\Lambda _{m2}}$$. The conductivities exhibited by these two cells are same. The relationship between $${\Lambda _{m2}}$$ and $${\Lambda _{m1}}$$ is

In which of the following half cells, electrochemical reaction is pH dependent?

In 3d series, the metal having the highest M²⁺/M standard electrode potential is :

The $${\left( {{{\partial E} \over {\partial T}}} \right)_P}$$ of different types of half cells are as follows:

(Where E is the electromotive force)

Which of the above half cells would be preferred to be used as reference electrode?

The correct order of reduction potentials of the following pairs is

A. Cl₂/Cl^$$-$$

B. I²/I^$$-$$

C. Ag⁺/Ag

D. Na⁺/Na

E. Li⁺/Li

Choose the correct answer from the options given below.