31.

Which one of the following impurities present in colloidal solution cannot be remove by electrodialysis ?

• Sodium chloride

• Potassium sulphate

• Urea

• Calcium chloride

The number of moles of lead nitrate needed to coagulate 2 moles of colloidal [AgI]I^- is

• 2

• 1

• 1/2

• 2/3

Plot of log x/m against log p is a straight line inclined at an angle of 45°. When the pressure is 0.5 atm and Freundlich parameter, k is 10, the amount of solute adsorbed per gram of adsorbent will be (log 5 = 0.6990).

• 1g

• 2g

• 3g

• 5g

On adding 1 mL of solution of 10% NaCl to 10 mL of gold sol in the presence of 0.25 g of starch, the coagulation is just prevented. The gold number of starch is

• 250

• 25

• 2.5

• 0.25

Lyophilic sols are more stable than lyophobic sols because the particles :

• are positively charged

• are negatively charged

• are solvated

• repel each other

Potassium stearate is obtained by the saponification of an oil or fat. It has the formula CH₃–(CH₂)₁₆ .The molecule has a lyophobic end [CH3] and a lyophilic 'end COO^- K⁺.Potassium stearate is an example for:

• lyophobic colloid

• associated colloid or micelle

• lyophilic colloid

• multimolecular colloid

On addition of 1 mL solution of 10% NaCl to 10 mL gold solution in the presence of 0.025 g of starch, the coagulation is prevented because starch has the following gold numbers :

• 25

• 0.025

• 0.25

• 2.5

When a beam of light is passed through a colloidal solution it :

• is reflected

• is scattered

• transmitted

• absorbed

The coagulating power of an electrolyte for arsenious sulphide decreases in the order :

• Na⁺ > Al³⁺ > Ba²⁺

• PO${}_4^{3-}$ > SO${}_4^{2-}$ > Cl^-

• Cl > SO${}_4^{2-}$ > PO${}_4^{3-}$

• Al³⁺ > Ba²⁺ > Na⁺

Colligative properties are used for the determination of :

• molar mass

• equivalent weight

• arrangement of molecules

• melting point and boiling point