A certain metal salt solutions is electrolysed in series with a silver coulometer. The weights of silver and the metal deposited are 0.5094 g and 0.2653 g. Calculate the valency of the metal if its atomic weight is nearly that of silver. 

(1) 1                                                 

(2) 2

(3) 3                                                 

(4) 4

The standard reduction potentials for $M{n}^{3+}/M{n}^{2+}$ and $Mn{O}_2<mspace\; width="1em"></mspace>/M{n}^{3+}$ couples in acid medium at $25°C$ are 1.50 V and 1.00 V respectively. The following reaction:

$2M{n}^{3+}<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>2H_{2}O<mspace\; width="1em"></mspace>\to <mspace\; width="1em"></mspace>M{n}^{2+}<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>Mn{O}_2<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>4H^{+}<mspace\; width="1em"></mspace>is$

(1) reversible                                             

(2) non-spontaneous

(3) spontaneous                                         

(4) irreversible

In a half-cell containing $\left[T{l}^{3+}\right]<mspace\; width="1em"></mspace>=<mspace\; width="1em"></mspace>0.1<mspace\; width="1em"></mspace>M<mspace\; width="1em"></mspace>and<mspace\; width="1em"></mspace>[T{l}^{+}<mspace\; width="1em"></mspace>]<mspace\; width="1em"></mspace>=<mspace\; width="1em"></mspace>0.01<mspace\; width="1em"></mspace>M,$ the cell potential is – 1.2496 V for the reaction $T{l}^{+}\to <mspace\; width="1em"></mspace>T{l}^{3+}<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>2e^{-}$  The standard reduction potential of the $T{l}^{+}<mspace\; width="1em"></mspace>/T{l}^{3+}$ couple at $25°C$ is

(1) 1.44 V                                          

(2) 0.61 V

(3) 2.44 V                                          

(4) 1.22 V

Given cell: 

Pt(s)|H₂(g)(P = 1 atm)| CH₃COOH(0.1 M), HCl(0.1 M) || KCl(aq)|Hg₂Cl₂(s)|Hg

EMF of the cell is found to be 0.045 V at 298 K and the temperature coefficient is 3.4×10^-4 V K^-1. The cell entropy change of the following cell is : 

[Given K_a CH₃COOH = 10^-5  M]

1. 70.8 J K⁻¹ mol⁻¹                      

2. 65.2 J K⁻¹ mol⁻¹

3. 79.2 J K⁻¹ mol⁻¹                  

4. 83.5 J K⁻¹ mol⁻¹

Adiponitrile is manufactured electrolytically from acrylonitrile $C{H}_2=<mspace\; width="1em"></mspace>CHCN<mspace\; width="1em"></mspace>\to <mspace\; width="1em"></mspace>CN<mspace\; width="1em"></mspace>–<mspace\; width="1em"></mspace>(C{H}_2<mspace\; width="1em"></mspace>{)}_4<mspace\; width="1em"></mspace>–<mspace\; width="1em"></mspace>CN$

The reduction potential of a half-cell consisting of a Pt electrode immersed in $1.5<mspace\; width="1em"></mspace>M<mspace\; width="1em"></mspace>F{e}^{2+}$and $0.015<mspace\; width="1em"></mspace>M<mspace\; width="1em"></mspace>F{e}^{3+}$ solution at $25°C<mspace\; width="1em"></mspace>is<mspace\; width="1em"></mspace>\left(E_{\left(F{e}^{+3},<mspace\; width="1em"></mspace>Fe+2\right)}^{°}=+0.770<mspace\; width="1em"></mspace>v\right)$.

(1) 0.652 V                                                   

(2) 0.88 V

(3) 0.710 V                                                   

(4) 0.850 V

In a concentration cell, $Zn/Z{n}^{2+}<mspace\; width="1em"></mspace>(1.0<mspace\; width="1em"></mspace>M)<mspace\; width="1em"></mspace>\left|\right|<mspace\; width="1em"></mspace>Z{n}^{2+}<mspace\; width="1em"></mspace>(0.15<mspace\; width="1em"></mspace>M)/Zn$ as the cell discharges,

(1) reaction proceeds to the right

(2) the two solutions approach each other in concentration

(3) no reaction takes place

(4) water gets decomposed

A dilute solution of $H_2<mspace\; width="1em"></mspace>S{O}_4$ was electrolysed by passing a current of 2 amp. The time required for formation of 0.5 mole of oxygen is

(1) 26.8 hours                                    

(2) 13.4 hours

(3) 6.7 hours                                      

(4) 28.6 hours

The temperature coefficient, of the emf is $\frac{d\epsilon }{dT}$= – 0.00065 volt. $de{g}^{-1}$ for the cell $Cd\left|CdC{l}_2\left(1m\right)\right|<mspace\; width="1em"></mspace>\left|\underset{\left(s\right)}{AgCl}\right|Ag<mspace\; width="1em"></mspace>at<mspace\; width="1em"></mspace>25°C$. Calculate the entropy change $∆S_{298K,<mspace\; width="1em"></mspace>}$ for the cell reaction,$Cd<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>2AgCl<mspace\; width="1em"></mspace>\to C{d}^{++}<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>2C{l}^{⊝}+<mspace\; width="1em"></mspace>2Ag$

$\left(1\right)<mspace\; width="1em"></mspace>–<mspace\; width="1em"></mspace>105.5<mspace\; width="1em"></mspace>J{K}^{-1}<mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace>$

$\left(2\right)<mspace\; width="1em"></mspace>–<mspace\; width="1em"></mspace>150.2<mspace\; width="1em"></mspace>J{K}^{-1}$

$\left(3\right)<mspace\; width="1em"></mspace>–<mspace\; width="1em"></mspace>75.5<mspace\; width="1em"></mspace>J{K}^{-1}$

$<mspace\; width="1em"></mspace>\left(4\right)<mspace\; width="1em"></mspace>–<mspace\; width="1em"></mspace>125.5<mspace\; width="1em"></mspace>J{K}^{-1}$