Constituents Of Air And Their Uses: Air is invisible to the eye because it contains colourless gases. The major constituents of dry air are nitrogen, oxygen, inert gases and carbon dioxide. Uses of Nitrogen (78.1%): Nitrogen dilutes the effect of oxygen. Oxygen supports burning and respiration. Nitrogen takes no part in burning. Any fire would spread quickly and it could never be put out if nitrogen were not present in the air. Nitrogen also reduces the rate of respiration by reducing the content of oxygen. If all the air were oxygen, the activity of our bodies would have been so … Continue reading Constituents Of Air And Their Uses