What is the difference between a mixture, compound, element and pure substance

mixture = when two or more substances combine without making a new substance.

compound = elements that are bonded together chemically

element = the simplest form of matter that cannot be broken down

pure substance = a substance made up of one compound

basically the differences are their definitions :D

altitude, density, pressure

air gets less dense the higher the altitude and also the air pressure is less as altitude rises.

possibly, yes.

explanation:

the amount of sugar you take in is dangerously high, risk of heart disease, high risk of diabetes, and etc.