Atmospheric pressure decreases as the height of a surface above ground level increases. This is because, as the altitude increases:
•the number of air molecules decreases •the weight of the air decreases •there is less air above a surface
This is why aircraft that fly at high altitudes must be pressurised. If the air pressure is too low, humans cannot take in oxygen quickly enough to meet their bodies’ needs.
Earthquakes. are caused by the earth's crust, more specifically, tectonic plates that float on top of molten magma. These plates bump into each other. it's the answer Earthquakes.
The multiring aromatic hydrocarbons in the coal liquid were hydrogenated to give saturated molecules that contained only one aromatic ring. Of the several organic bases investigated, potassium bis(trimethylsilyl)amide was found to be the most effective catalyst.
