EMF of hydrogen electrode in term of pH is (at 1 atm pressure).

• ${\mathrm{E}}_{{\mathrm{H}}_2}=\frac{\mathrm{RT}}{\mathrm{F}}\times \mathrm{pH}$

• ${\mathrm{E}}_{{\mathrm{H}}_2}=\frac{\mathrm{RT}}{\mathrm{F}}·\frac{1}{\mathrm{pH}}$

• ${\mathrm{E}}_{{\mathrm{H}}_2}=\frac{2.303 \mathrm{RT}}{\mathrm{F}}\mathrm{pH}$

• ${\mathrm{E}}_{{\mathrm{H}}_2}=- 0.591 \mathrm{pH}$

For the cell reaction, 

2Ce⁴⁺ + Co → 2Ce³⁺ + Co³⁺; E${}_{\mathrm{cell}}^{°}$ is 1.89 V. If ${\mathrm{E}}_{{\mathrm{Co}}^{2+}/ \mathrm{Co}}$ is -0.28V, what is the value of ${\mathrm{E}}_{{\mathrm{Ce}}^{4+} / {\mathrm{Ce}}^{3+}}^{°}$?

• 0.28 V

• 1.61 V

• 2.17 V

• 5.29 V

73.

The equivalent conductance of silver nitrate solution at 250°C for an infinite dilution was found to be 133.3 $\mathrm{\Omega }$^-1 cm² equiv^-1. The transport number of Ag⁺ ions in very dilute solution of AgNO₃ is 0.464. Equivalent conductances of Ag⁺ and NO₃^- (in Ω^-1 cm² equiv^-1) at infinite dilution are respectively.

• 195.2; 133.3

• 61.9; 71.4

• 71.4; 61.9

• 133.3; 195.2

The standard reduction potential for Mg²⁺ /Mg is - 2.37 V and for Cu²⁺ /Cu is 0.337. The E${}_{\mathrm{cell}}^{°}$ for the following reaction is

Mg + Cu²⁺ → Mg²⁺ + Cu

• +2.03 V

• -2.03 V

• -2.7 V

• +2.7 V

Cu⁺ (aq) is unstable in solution and undergoes simultaneous oxidation and reduction, according to the reaction

                    $2{\mathrm{Cu}}^{+}\left(\mathrm{aq}\right) \rightleftharpoons {\mathrm{Cu}}^{+}\left(\mathrm{aq}\right) + \mathrm{Cu}\left(\mathrm{s}\right)$

choose correct E° for above reaction if

${\mathrm{E}}_{{\mathrm{Cu}}^{2+}/\mathrm{Cu}}^{°}= 0.34 \mathrm{V} \mathrm{and}\hspace{0.17em}{\mathrm{E}}_{{\mathrm{Cu}}^{2+}/{\mathrm{Cu}}^{+}}^{°} = 0.15 \mathrm{V}$

• -0.38 V

• + 0.49 V

• + 0.38 V

• -0.19 V

The number of electrons required to reduce 4.5 × 10^-5 of Al is

• 1.03 × 10¹⁸

• 3.01 × 10¹⁸

• 4.95 × 10²⁶

• 7.31 × 10²⁰

The standard reduction potentials at 298 K for the following half-cell reactions are given on next page

                    $$\begin{gathered} {\mathrm{Zn}}^2\left(\mathrm{aq}\right)\hspace{0.17em}+ 2{\mathrm{e}}^{-} \rightleftharpoons \mathrm{Zn}\left(\mathrm{s}\right)\hspace{0.17em}-0.762 \\ {\mathrm{Cr}}^{3+}\left(\mathrm{aq}\right)\hspace{0.17em}+ 3{\mathrm{e}}^{-} \rightleftharpoons \mathrm{Cr}\left(\mathrm{s}\right)\hspace{0.17em}-0.74 \\ 2{\mathrm{H}}^{+}\left(\mathrm{aq}\right)\hspace{0.17em}+ 2{\mathrm{e}}^{-} \rightleftharpoons {\mathrm{H}}_2\left(\mathrm{g}\right)\hspace{0.17em}+0.00 \\ {\mathrm{Fe}}^{3+}\left(\mathrm{aq}\right)\hspace{0.17em}+ {\mathrm{e}}^{-} \rightleftharpoons {\mathrm{Fe}}^{2+}\left(\mathrm{aq}\right) +0.77 \end{gathered}$$

Which one of the following is the strongest reducing agent?

• Zn(s)

• Cr(s)

• H₂(s)

• Fe²⁺(aq)

1 C electricity deposits

• 10.8 g of Ag

• 96500 g of Ag

• electrochemical equivalent of Ag

• half of electrochemical equivalent of Ag

Given, for Sn⁴⁺/ Sn²⁺, standard reductiona potential is 0.15 V and for Au³⁺/ Au, standard reduction potential is 1.5 V.

For the reaction,

3Sn²⁺ + 2Au³⁺ → 3Sn⁴⁺ + 2Au

the value of E${}_{\mathrm{cell}}^{°}$ is

• +1.35

• +2.55

• -1.35

• -2.55

The isotope tha causes skin disease is

• I¹³¹

• S³⁵

• P³¹

• None of these