Correct option is D
When the dispersed phase is gas and the dispersing medium is solid, the type of colloid is called foam. In such a colloidal system, gas bubbles are dispersed in a solid medium, forming structures like foamed rubber, sponges, or pumice stone. The gas pockets are trapped within the solid matrix, giving the material its characteristic structure.
An
emulsion is a colloidal system where the
dispersed phase is liquid and the
dispersing medium is also liquid. Examples include milk, mayonnaise, and creams, where one liquid is dispersed within another liquid.
A
gel is a colloidal system where the
dispersed phase is solid and the
dispersing medium is liquid. Gels are semi-solid systems like gelatin, which consist of solid particles dispersed in a liquid medium.
An
aerosol is a colloid where the
dispersed phase is solid or liquid and the
dispersing medium is gas. Common examples include fog (liquid in gas) and smoke (solid in gas).
