A hypothetical electrochemical cell is shown below.
A|A⁺(x M) || B⁺(y M)|B
The Emf measured is +0.20 V. The cell reaction is:

1. A⁺ + B → A + B⁺

2.  A⁺ + e^- → A ; B⁺ + e^- → B

3. The cell reaction cannot be predicted.

4. A + B⁺ → A⁺ + B

A solution containing one mole per litre each of Cu(NO₃)₂, AgNO₃, Hg₂(NO₃)₂ and Mg(NO₃)₂ is being electrolyzed by using inert electrodes. The values of standard electrode potentials in volt (reduction potentials) are,

Ag⁺ /Ag = 0.80 V, ${\mathrm{Hg}}_2^{2+}$/2Hg = 0.79 V,

Cu²⁺/Cu = +0.34 V and Mg²⁺/Mg = -2.37 V

With increasing voltage, the sequence of deposition of metals on the cathode will be:

1. Ag, Hg, Cu, Mg

2. Mg, Cu, Hg, Ag

3. Ag, Hg, Cu

4. Cu, Hg, Ag

The negative sign in the expression E^o_Zn²⁺/Zn = -0.76 V indicates : 

1. The reactivity of the metal increases.

2. The reactivity of the metal decreases.

3. There is no effect on the metal's reactivity.

4. None of the above.

The standard reduction electrode potentials of three metals X, Y, and Z are given as -1.2 V, +0.5 V, and -3.0 V, respectively. Based on these values, what is the correct order of their reducing power?

The most stable oxidized species among the following is: 
\(E_{{\mathrm{Cr}_2 \mathrm{O}_7^2}/ \mathrm{Cr}^{3+}}^{o} =1.33 \mathrm{~V} ; E_{\mathrm{Cl}_2 / \mathrm{Cl}^{-}}^{o}=1.36 \mathrm{~V} \)
\( E_{\mathrm{MnO_{4}}^{-} / \mathrm{Mn}^{2+}}^{o}=1.51 \mathrm{~V} ; E_{\mathrm{Cr}^{3+} / \mathrm{Cr}}^{o}=-0.74 \mathrm{~V}\)

When a copper wire is immersed in a solution of AgNO₃, the colour of the solution becomes blue because copper:

1. Forms a soluble complex with \(AgNO_3\)
2. Is oxidised to \(Cu^{2+}\)
3. Is reduced to \(Cu^{2-}\)
4. Splits up into atomic form and dissolves

Without losing it's concentration, ZnCl₂ solution cannot be kept in contact with :

1. Au

2. Al

3. Pb

4. Ag

If an iron rod is dipped in CuSO₄ solution, then:

1. Blue colour of the solution turns red.

2. Brown layer is deposited on iron rod.

3. No change occurs in the colour of the solution.

4. None of the above.