Li occupies a higher position in the electrochemical series of metals as compared to Cu since :

• the standard reduction potential of Li⁺/Li is lower than that of Cu²⁺/Cu

• the standard reduction potential of Cu²⁺/Cu is lower than that of Li⁺/Li

• the standard oxidation potential of Li⁺/Li is lower than that of Cu²⁺/Cu

• Li is smaller in size as compared to Cu

A hydrogen gas electrode is made by dipping platinum wire in a solution of HCl of pH=10 and by passing hydrogen gas around the platinum wire at 1 atm pressure. The oxidation potential of electrode would be

• 0.059 V

• 0.59 V

• 0.118V

• 1.18V

At 25°C molar conductance of 0.1 molar aqueous solution of ammonium hydroxide is 9.54 ohm^-1cm² mol^-1 and at infinite dilution its molar conductance is 238 ohm^-1cm² mol^-1. The degree of ionisation of ammonium hydroxide at the same concentration and temperature is

• 2.080%

• 20.800%

• 4.008%

• 40.800%

394.

A button cell used in watches functions as following

$$\begin{gathered} \mathrm{Zn}\left(\mathrm{s}\right)\hspace{0.17em}+\hspace{0.17em}{\mathrm{Ag}}_2\mathrm{O}\left(\mathrm{s}\right)\hspace{0.17em}+\hspace{0.17em}{\mathrm{H}}_2\mathrm{O} \left(\mathrm{l}\right)\hspace{0.17em} \rightleftharpoons 2\mathrm{Ag}\left(\mathrm{s}\right)\hspace{0.17em}+{\mathrm{Zn}}^{2+}\left(\mathrm{aq}\right)\hspace{0.17em}+\hspace{0.17em}2{\mathrm{OH}}^{-}\left(\mathrm{aq}\right) \\ \mathrm{If}\hspace{0.17em}\mathrm{half}\hspace{0.17em}\mathrm{cell}\hspace{0.17em}\mathrm{potentials}\hspace{0.17em}\mathrm{are}\hspace{0.17em} \\ {\mathrm{Zn}}^{2+}\left(\mathrm{aq}\right)\hspace{0.17em}+\hspace{0.17em}2{\mathrm{e}}^{-} \to \mathrm{Zn}\hspace{0.17em}\left(\mathrm{s}\right); {\mathrm{E}}^{°} = -0.76 \mathrm{V} \\ {\mathrm{Ag}}_2\mathrm{O}\left(\mathrm{s}\right)\hspace{0.17em}+\hspace{0.17em}{\mathrm{H}}_2\mathrm{O} \left(\mathrm{l}\right)\hspace{0.17em}+ 2{\mathrm{e}}^{-}\to 2\mathrm{Ag}\left(\mathrm{s}\right)\hspace{0.17em}+\hspace{0.17em}2{\mathrm{OH}}^{-}\left(\mathrm{aq}\right), {\mathrm{E}}^{°} = 0.34 \mathrm{V} \\ \mathrm{The}\hspace{0.17em}\mathrm{cell}\hspace{0.17em}\mathrm{potential}\hspace{0.17em}\mathrm{will}\hspace{0.17em}\mathrm{be} \end{gathered}$$

• 1.10 V

• 0.42 V

• 0.84 V

• 1.34 V

The quantity of electricity needed to separately electrolyze 1 M solution of ZnSO₄ , AlCl₃ and AgNO₃ completely is in the ratio of

• 2 : 3 : 1

• 2 : 1 : 1

• 2 : 1 : 3

• 2 : 2 : 1

On passing C ampere of current for the time 't' sec through 1 L of 2 (M) CuSO₄ solution (atomic weight of Cu= 63. 5), the amount 'm' of Cu (in gram) deposited on cathode will be

• m = Ct/(63.5 x 96500)

• m = Ct/(31.25 X 96500)

• m = (C x 96500)/(31.25 x t)

• m = (31.25 X C x t)/96500

The two half-cell reactions of an electrochemical cell is given as

Ag⁺ + e^- → Ag; ${\mathrm{E}}_{{\mathrm{Ag}}^{+}/ \mathrm{Ag}}^{°}$ = -0.3995 V

Fe²⁺ → Fe³⁺ + e^- ; ${\mathrm{E}}_{{\mathrm{Fe}}^{3+}/ {\mathrm{Fe}}^{2+}}^{°}$ = -0.7120 V

The value of cell EMF will be

• -0.3125 V

• 0.3125 V

• 1.114 V

• -1.114 V

At 25°C, the molar conductance of 0.007 M hydrofluoric acid is 150 mho cm²mol^-1 and its Λ°_m = 500 cm²mol^-1. The value of the dissociation constant of the acid at the given concentration at 25°C is

• 7 × 10^-4 M

• 7 × 10^-5 M

• 9 × 10^-3 M

• 9 × 10^-4 M

The standard reduction potential E^o for half-reaction are:

Zn $\to$ Zn²⁺ + 2e^- ; E° = + 0.76V

Fe $\to$ Fe²⁺ + 2e^- ; E° = + 0.41 V

The EMF of the cell reaction

Fe²⁺ + Zn $\to$ Zn²⁺ + Fe is :

• - 0.35 V

• + 0.35 V

• + 1.17 V

• - 1.17 V

The formal potential of Fe³⁺ /Fe²⁺ in a sulphuric acid and phosphoric acid mixture (E° = +0.61 V) is much lower than the standard potential (E° = +0.77 V). This is due to

• formation of the species [FeHPO₄]⁺

• lowering of potential upon complexation

• formation of the species [FesO₄]+

• high acidity of the medium