SURFACE CHEMISTRY

At the equilibrium position in the process of adsorption ___________.

• ΔH > 0

• ΔH = TΔS

• ΔH > TΔS

• ΔH < TΔS

The term ‘sorption’ stands for ____________.

• absorption

• adsorption

• both absorption and adsorption

• desorption

Extent of physisorption of a gas increases with ___________.

• increase in temperature.

• decrease in temperature.

• decrease in surface area of adsorbent.

• decrease in strength of van der Waals forces.

Which one of the following is not applicable to the phenomenon of adsorption?

• ΔH > 0

• ΔG < 0

• ΔS < 0

• ΔH < 0

Which of the following is not a favourable condition for physical adsorption?

• high pressure

• negative ΔH

• higher critical temperature of adsorbate

• high temperature

In physisorption adsorbent does not show specificity for any particular gas because ______________.

• involved van der Waals forces are universal.

• gases involved behave like ideal gases.

• enthalpy of adsorption is low.

• it is a reversible process.

At high concentration of soap in water, soap behaves as ____________.

• molecular colloid

• associated colloid

• macromolecular colloid

• lyophilic colloid

Freshly prepared precipitate sometimes gets converted to colloidal solution by ___________.

• coagulation

• electrolysis

• diffusion

• peptisation

Which of the following electrolytes will have maximum coagulating value for AgI/Ag+ sol?

•  $Na_2S$  

•  $Na_3PO_4$  

•  $Na_2SO_4$  

• NaCl

Which of the following process is responsible for the formation of delta at a place where rivers meet the sea?

• Emulsification

• Colloid formation

• Coagulation

• Peptisation