Surface Chemistry

Which of the following statement is not correct?

• Adsorption energy for chemical adsorption is generally greater than that of physical adsorption

• Physical adsorption is due to van der Waal forces

• Physical adsorption decreases at high temperature and low pressure

• Physical adsorption is irreversible

Solvent loving colloids are known as

• hydrophobic

• lyophilic

• hydrophilic

• none of these

Freundlich adsorption isotherm gives a straight line on plotting:

• $\frac{\mathrm{x}}{\mathrm{m}}$ vs p

• log $\frac{\mathrm{x}}{\mathrm{m}}$ vs p

• log $\frac{\mathrm{x}}{\mathrm{m}}$ vs log p

• $\frac{\mathrm{x}}{\mathrm{m}}$ vs $\frac{1}{\mathrm{p}}$

Arsenic sulphide sol is prepared by passing H₂S through arsenic oxide solution. The charge developed on the particles is due to adsorption of :

• H⁺

• S^2-

• OH^-

• O^2-

Which one of the following colloidal solution is positive sol?

• Gelatin in strongly acidic solution

• Smoke

• Dlay soil

• Blood

Gasoline is

• C₁₇H₃₆ to C₂₁H₅₀

• C₇H₂₄ to C₁₄H₃₄

• C₇H₁₆ to C₁₀H₂₂

• C₃H₈ to C₆H₁₄

A emulsifier is a substance which :

• stabilises the emulsion

• homogenises the emulsion

• coagulates the emulsion

• accelerates the dispersion of liquid in liquid

The coagulation of 200 mL of a positive colloid took place when 0.73 g HCl was added to it without changing the volume much. The flocculation value of HCl for the colloid is

• 100

• 36.5

• 0.365

• 150

Paints and hair creams are respectively

• sol and emulsion

• aerosol and foam

• emulsion and sol

• foam and gel.

Extent of adsorption of adsorbate from solution phase increases with :

• increase in amount of adsorbate in solution

• decrease in surface area of adsorbent

• increase irtemperature of solution

• decrease in amount of adsorbate in solution