The electrode potentials for

${\mathrm{Cu}}^{2+}\left(\mathrm{aq}\right) + {\mathrm{e}}^{-} \stackrel{ }{\to }{\mathrm{Cu}}^{+}\left(\mathrm{aq}\right)$
$\mathrm{and} {\mathrm{Cu}}^{+}\left(\mathrm{aq}\right) + {\mathrm{e}}^{-} \stackrel{ }{\to \mathrm{Cu}\left(\mathrm{s}\right)}$

are +0.15 V and +0.50 V respectively. The value of $E_{\raisebox{1ex}{${\mathrm{Cu}}^{2+}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{Cu}$}\right.}^{\circ }\mathit{ }$will be

1. 0.325 V

2. 0.650 V

3. 0.150 V

4. 0.500 V

The Zn acts as sacrificial or cathodic protection to prevent rusting of iron because:

1. $E_{OP}^{\circ }$ of Zn < $E_{OP}^{\circ }$ of Fe

2. $E_{OP}^{\circ }$ of Zn > $E_{OP}^{\circ }$ of Fe

3. $E_{OP}^{\circ }$ of Zn = $E_{OP}^{\circ }$ of fe

4. Zn is cheaper than iron

The standard reduction potential for Fe²⁺|Fe and Sn²⁺|Sn electrodes are -0.44 V and -0.14 V respectively. For the cell reaction,

Fe²⁺ + Sn  →  Fe + Sn²⁺, the standard Emf is - 

1. +0.30 V

2. 0.58 V

3. +0.58 V

4. -0.30 V

On electrolysing a solution of dilute H₂SO₄ between platinum electrodes, the gas evolved at the anode and cathode are respectively:

1. SO₂ and O₂

2. SO₃ and H₂

3. O₂ and H₂

4. H₂ and O₂

In electrolysis of NaCl when Pt electrode is taken then H₂ is liberated at cathode while with Hg cathode it forms sodium amalgam because :

1. Hg is more inert than Pt

2. More voltage is required to reduce H⁺ at Hg than at Pt

3. Na is dissolved in Hg while it does not dissolve in Pt

4. Concentration of H⁺ ions is larger when Pt electrode is taken.

If mercury is used as cathode in the electrolysis of aqueous NaCl solution, the ions discharged at cathode are:

1. H⁺

2. Na⁺

3. OH^-

4. Cl^-

Standard Reduction electrode potential of three metals X, Y, and Z are -1.2 V, +0.5 V and -3 V respectively. The reducing power of these metals will be : 

A gas X at 1 atm is bubbled through a solution containing a mixture of 1MY^- and 1MZ^- at 25$°$C. If the reduction potential of Z > Y > X, then:

1. Y will oxidise X and not Z

2. Y will oxidise Z and not X

3. Y will oxidise both X and Z

4. Y will reduce both X and Z

The solution of CuSO₄ in which copper rod is immersed is diluted to 10 times, the reduction electrode potential:

1. increases by 0.030 V

2. decreases by 0.030 V

3. increases by 0.059 V

4. decreases by 0.059 V

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