$E_{\raisebox{1ex}{${\mathrm{Fe}}^{2+}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{Fe}$}\right.}^{\circ }<mspace\; width="1em"></mspace>=<mspace\; width="1em"></mspace>-0.441<mspace\; width="1em"></mspace>\mathrm{V}<mspace\; width="1em"></mspace>and<mspace\; width="1em"></mspace>E_{\raisebox{1ex}{${\mathrm{Fe}}^{3+}$}\!\left/ \!\raisebox{-1ex}{${\mathrm{Fe}}^{2+}$}\right.}^{\circ }<mspace\; width="1em"></mspace>=0.771<mspace\; width="1em"></mspace>\mathrm{V}$, the standard emf of the reaction

$\mathrm{Fe}<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>2{\mathrm{Fe}}^{3+}<mspace\; width="1em"></mspace>\stackrel{<mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace>}{\to }3{\mathrm{Fe}}^{2+}$will be

1. 0.111V

2. 0.330V

3. 1.653V

4. 1.212V

The standard electrode potential for Sn⁴⁺/Sn²⁺ couple is +0.15 V and that for the Cr³⁺/Cr couple is -0.74 V. These two couples in their standard state are connected to make a cell. The cell potential will be: 

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.

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

1. Au

2. Al

3. Pb

4. Ag

The standard reduction potential at 290 K for the following half reactions are,

(i) Zn²⁺ + 2e— → Zn(s);      E° = -0.762 V

(ii) Cr³⁺ + 3e → Cr(s);          E° = -0.740 V

(iii) 2H⁺ + 2e → H₂(g); ·      E° = +0.000 V

(iv) Fe³⁺ + e → Fe²⁺;         E° = +0.77V

Which is the strongest reducing agent?

1. Zn

2. Cr

3. Fe²⁺

4. H₂

Which graph correctly correlates E_cell as a function of concentrations for the cell (for different values of M and M') ?

$\mathrm{Zn}\left(\mathrm{s}\right)<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>{\mathrm{Cu}}^{2+}\left(M\right)<mspace\; width="1em"></mspace>\stackrel{<mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace>}{\to }{\mathrm{Zn}}^{2+}(M\text{'})<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>\mathrm{Cu}\left(\mathrm{s}\right);$
$<mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace>E_{\mathrm{cell}}^{\circ }<mspace\; width="1em"></mspace>=<mspace\; width="1em"></mspace>1.10<mspace\; width="1em"></mspace>\mathrm{V}$
$X-\mathrm{axis}<mspace\; width="1em"></mspace>:<mspace\; width="1em"></mspace>{\log }_{10}\frac{\left[{\mathrm{Zn}}^{2+}\right]}{\left[{\mathrm{Cu}}^{2+}\right]},<mspace\; width="1em"></mspace>Y-\mathrm{axis}<mspace\; width="1em"></mspace>:<mspace\; width="1em"></mspace>E_{\mathrm{cell}}<mspace\; width="1em"></mspace>$

1.                         2.    
3.                         4. 

An iron ship is continuously exposed to seawater, which can cause corrosion (rusting) of its hull.
Which of the following methods provides the most effective long-term protection
to the iron at the bottom of the ship? 

1. Coat the iron surface with red lead oxide paint

2. Cover the iron surface with a layer of tin (tin plating) 

3. Attach blocks of magnesium to the iron hull

4. Attach blocks of lead to the iron hull

The electrode potentials for

$<mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace>{\mathrm{Cu}}^{2+}\left(\mathrm{aq}\right)<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>{\mathrm{e}}^{-}<mspace\; width="1em"></mspace>\stackrel{<mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace>}{\to }{\mathrm{Cu}}^{+}\left(\mathrm{aq}\right)$
$\mathrm{and}<mspace\; width="1em"></mspace>{\mathrm{Cu}}^{+}\left(\mathrm{aq}\right)<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>{\mathrm{e}}^{-}<mspace\; width="1em"></mspace>\stackrel{<mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace>}{\to <mspace\; width="1em"></mspace>\mathrm{Cu}\left(\mathrm{s}\right)}$

are +0.15 V and +0.50 V respectively. The value of $E_{\raisebox{1ex}{${\mathrm{Cu}}^{2+}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{Cu}$}\right.}^{\circ }\mathit{\hspace{0.17em}}$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