Question

A suspension of liquid droplets or fine solid particles in a gas is called:
A.Aerosol
B.Particulate
C.Both a and b
D.Colloid

Answer 1

Hint: Use the basic definition of the given terms. These particles can be created by nature or can be exerted by human activities. Examples of these can be smoke, fumes, soot etc. An example for these particles which are exerted by the human activities can be smoke from the industries.

Complete answer:
Aerosol is an abbreviation for aero-solution. Aerosol can be defined as a suspension of liquid droplets or fine solid particles in air, or any other gas. There are two types of aerosols namely natural and anthropogenic. Natural aerosols are the ones which are created naturally in nature. Examples of such aerosols can be fog, dust, etc. Anthropogenic aerosols are the ones which are released in the atmosphere due to human activities. Examples of such aerosols can be smoke released from the industries, smoke released from the exhausts and other human activities.
Particulates are the matter which are a combination of solids and liquids that are suspended in air. These particles are generally hazardous. These particles vary based on size, composition or origin. Particulates include soot, moist, smoke, fumes, etc. When fuel is burnt and the dust is carried by the wind, then these particles are emitted directly.
Colloids are the mixtures in which microscopically dispersed insoluble particles of one substance are suspended in another substance. The particles of colloids are so small that it cannot be seen by naked eyes. These mixtures cannot be separated using a filtration process. It can be separated only by the process of Centrifugation. Examples of colloids include whipped cream, butter, gelatin, paper etc.
Thus, a suspension of liquid droplets or fine particles in a gas is called Aerosol as well as Particulate.

Hence, the correct answer is option C i.e. both a and b.

Note: To answer such types of questions you must have a knowledge about the terms mentioned above. When suspension of liquid droplets take place, it is known as Liquid aerosol. When suspension of fine solid particles in a gas takes place, it is known as Solid aerosol.