Chapter 5: Surface Chemistry

Option (i) and (ii) are the answers.

Option (i) and (iv) are the answers.

III. Short Answer Type

In the adsorption process, the surface of adsorbent adsorbs the desired gases. If the surface is already occupied by some other gases, it becomes saturated and thus cannot adsorb desired gases

Chemisorption involves chemical bond formation which requires activation energy. That is why it is referred to as activated adsorption

Soap solution at low concentration behaves like normal electrolytic solution. But at high concentration soap solution behaves as associated colloid and form micelles.

When gelatin is mixed with gold sol, gelatin forms a protective layer on gold sol, thus preventing coagulation. So gold sol becomes stabilized by adding gelatin, which is a lyophilic sol.

Clouds carry a charge as they are colloids. Silver iodide AgI being an electrolyte helps in coagulation process between colloidal particles of water in the cloud. Thus it forms bigger raindrops causing artificial rain. AgI is usually sprayed from an aeroplane or remote-controlled rockets.

Gelatin acts as an emulsifying agent which is a hydrophilic colloid. They absorb the water content in the ice-cream and also a good source of protein. They also give a soft texture and shiny appearance to ice-cream.

Solution coming soon.

Alum is KAl(SO4)₂ which is called potassium aluminium sulphate. when added react with alkaline bicarbonates and forms a gelatinous precipitate. When it is added to water they attract the colloidal particles and settles down at the bottom of the container.