mentioned any four characteristics of air
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Answer:
Air takes up space. It's made up of atoms and molecules. ...
Air is made of gases, including nitrogen, oxygen, water vapor, and other materials. These substances are what give air mass.
Air exerts pressure. ...
Air has weight. ...
Air can be compressed. ...
Air is affected by temperature.
It is desirable to review the characteristics of air and the properties of airborne contaminants to provide a background for the design of industrial ventilation systems. The purpose of this chapter is to undertake such a review. As a gas, air can be compressed, that is, the molecules can be moved closer together. If no force compresses the air, it will expand indefinitely to fill the space available. The volume occupied by a given amount of gas varies with the temperature and pressure of the gas. This fact yelds several important standard values that are useful when working with air. The first of these is the specific weight, which is the weight in pounds of one cubic foot of a gas at a given temperature and pressure. The reciprocal of the specific weight is the specific volume, that is, the volume that one pound of a gas will occupy at a given temperature and pressure. Air usually has some moisture content. In many cases, this moisture content is very low; therefore, the error that is introduced by not including the measurement in calculations is not significant. However, there are situations where the amount of moisture in the air is significant and must be considered while designing ventilation systems.