Why should scientists perform expierements

Experiments are most useful when investigating predictions derived from explicit theories, and it is theories, rather than experimental results, that are properly used to explain features of natural settings.

altitude, density, pressure

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

the number of protons in the nucleus of a given element. has slight luster and conducts electricity at high temperatures like metal.but like a nonmetal,boron is brittle and does not conduct electricity well at low temperatures. in graphite, carbon is a soft,brittle solid.it is reflective,ductile,or malleable.