The separation of colloidal particles (or purification of sol) from particles of molecular dimensions is known as:

1. Photolysis

2. Dialysis

3. Pyrolysis

4. Peptization

How can alum help in water purification?

Lyophilic sols are:

(1) Irreversible sols

(2) They are prepared from inorganic compounds

(3) Not coagulated by adding electrolytes

(4) Self-stabilizing

The volume of colloidal particles $V_c$ as compared to the volume of solute particles in true solution $V_s$ could be:

(1) $~$1

(2) $~{10}^3$

(3) $~{10}^2$

(4) $~{10}^{-3}$

The dispersed phase in colloidal iron (III) hydroxide and colloidal gold is positively and negatively charged respectively, which of the following statement is not correct?

(1) MgCl₂ solution coagulates gold sol readily than iron (III) hydroxide sol  at pH = 7

(2) Na₂SO₄ solution causes coagulation in both sol

(3) Mixing of two sols have no effect

(4) Coagulation in both sol can be brought about by electrophoresis

Pick out the wrong statement.

1. Micelles are formed by surfactant molecules above the Critical Micelle Concentration (CMC)

2. The conductivity of a solution having surfactant molecules decreases sharply at the CMC

3. Lower is the CMC of detergent, more is its detergency

4. Cleansing action is not related to micelles

Among the following surfactant molecules, the surfactant with the lowest CMC in aqueous solution at ambient conditions is:

1. CH₃(CH₂)₁₅N⁺(CH₃)₃Br^-

2. CH₃(CH₂)₁₁OSO₃^- Na⁺

3. CH₃(CH₂)₆COO^-Na⁺

4. CH₃(CH₂)₁₁N⁺(CH₃)₃Br^-

Among the electrolytes Na₂SO₄, CaCl₂, Al₂(SO₄)₃ and NH₄Cl, the most effective coagulating agent for Sb₂S₃ sol is:

(1) Na₂SO₄

(2) CaCl₂

(3) Al₂(SO₄)₃

(4) NH₄Cl

Which ore contains both iron and copper ?

1. Cuprite

2. Chalcocite

3. Chalcopyrite

4. Malachite

The extraction of copper from chalopyrite  involved partial roasting, removal of iron and self-reduction.

In self-reduction, the reducing species is

(1) S

$\left(2\right)<mspace\; width="1em"></mspace>O^{2-}$
$$
$\left(3\right)<mspace\; width="1em"></mspace>S^{2-}$
$$
$\left(4\right)<mspace\; width="1em"></mspace>S{O}_2$