Given the following cell:

\(\small{Pt(s)|Br_{2}(l)|Br^{-}(0.010 \ M)\ || H_{2}(g)(1\ bar)|H^{+}(0.030 \ M)|Pt(s)}\)

If the concentration of \(Br^-\) becomes 2 times and the concentration of \(H^+\) becomes half of the initial value, then emf of the cell will become:

1. Two times.

2. Four times.

3. Eight times.

4. Remains the same.

Adding powdered lead and iron to a solution that is 1.0 molar each in ${\mathrm{Pb}}^{2+}$ and ${\mathrm{Fe}}^{2+}$ ions, would result to a reaction in which

     $\begin{array}{rl}& {\mathrm{E}}_{{\mathrm{Fe}}^{2+}/\mathrm{Fe}}^{\circ }=-0.44\mathrm{V}\\ & {\mathrm{E}}_{{\mathrm{Pb}}^{2+}/\mathrm{Pb}}^0=-0.13\mathrm{V}\end{array}$

1.  Conc. of both ${\mathrm{Pb}}^{2+}$ and ${\mathrm{Fe}}^{2+}$ are increased

2.  More lead and iron are formed

3.  More of iron and ${\mathrm{Pb}}^{2+}$ ions are formed

4.  More of lead and ${\mathrm{Fe}}^{2+}$ ions are formed

The useful work of the reaction \(\small{\mathrm{Ag}(\mathrm{s})+1 / 2 \mathrm{Cl}_2(\mathrm{~g}) \rightarrow \mathrm{AgCl}(\mathrm{s})}\) is: 

Given,
\(E_{Cl_{2}/Cl^{-}}^{o} \ = \ +1.36 \ V, \)
\(E_{AgCl/Ag, / Cl^{-}}^{o} \ = \ 0.22 \ V, \)
\( P_{Cl_{2}} \ = \ 1 \ atm\ and \)
\( T = 298 K\)

The temperature coefficient of a standard Cd-cell is $–5.0 \times {10}^{-5} V{k}^{-1}$ whose emf at $25°C$ is 1.018 V. During the cell operation, the temperature will -

(1) increase                                      

(2) decreases

(3) either                                         

(4) remains constant

$The Cell Pt\left(H_2\right)(1 atm)\left|H^{\oplus }\right(pH=?),I^{\oplus }(a=1\left)\right|AgI\left(s\right),$Ag has emf, $E_{298}=0$. The electrode potential for the reaction AgI + $e^{-}\to Ag+I^{\oplus }$ is -0.151 volt. Calculate the pH value.

(A) 3.37                                                           

(B) 5.26

(C) 2.56                                                           

(D) 4.62

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. 

(A) 1                                                 

(B) 2

(C) 3                                                 

(D) 4

Adiponitrile is manufactured electrolytically from acrylonitrile. The reaction is as follows:
$C{H}_2=$ $CHCN$ $\to$ $CN$ $–$ $(C{H}_2$ ${)}_4$ $–$ $CN$

How many kg of adiponitrile (molecular mass = 108) is produced in 9.65 hr using a current of 3750 A with 80 % efficiency?

1. 30 kg                                               

2. 58 kg

3. 60 kg                                               

4. 80 kg

 $E^0 for the reaction$
$Fe + Z{n}^{2+} = Zn + F{e}^{2+} is – 0.35 V.$
$The given cell reaction is-$ 

(A) Feasible                                                                  

(B) Not feasible

(C) In equilibrium                                                         

(D) None

The metal that cannot be produced upon reduction of its oxide by aluminium is :

Given that a certain electric current generates 0.504 grams of hydrogen in 2 hours. How many gram of mass of copper can be liberated by the same current when applied for the same duration in a solution of CuSO₄?

1. 12.7

2. 16

3. 31.8

4. 63.5