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

Al₂O₃ is reduced by electrolysis at low potentials and high currents. If 4.0 x 10⁴ A of current is passed through molten Al₂O₃ for 6 h, what mass of aluminium is produced? (Assume 100% current efficiency, atomic mass of Al = 27g mol^-1)

1. 9.0 x 10³ g 

2.  8.1 x 10⁴ g

3.  2.4 x 10⁵ g

4.  1.3 x 10⁴ g

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') ?

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

1.                         2. 
3.                         4. 

The most convenient method to protect the bottom of the ship made of iron is 

1. coating it with red lead oxide

2. white tin plating 

3. connecting it with Mg block

4. connecting it with Pb block

When 0.1 mole of MnO^2-₄ is oxidised, the quantity of electricity required to completely oxidise MnO^2-₄ to MnO^-₄ is 

1. 96500 C

2. 2*96500 C 

3. 9650 C

4. 96.50 C

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