Answer:
not sure if this is the right way to answer this question but PbS is Phosphate-buffered saline (i think)
Explanation:
There are four main types of air pollution sources:
<span>mobile sources – such as cars, buses, planes, trucks, and trainsstationary sources – such as power plants, oil refineries, industrial facilities, and factoriesarea sources – such as agricultural areas, cities, and wood burning fireplaces<span>natural sources – such as wind-blown dust, wildfires, and volcanoes........hope i helped</span></span>
A pure substance has a constant composition and cannot be separated into simpler substances by physical means. There are two types of pure substances: elements and compounds. Elements: are pure substances made up of only l type of atom. Atoms of the same element are identical in properties.
