Please help me, I'm stuck and I don't know how to do it. How many atoms are there in 7.02 g Si ?

altitude, density, pressure

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

if two electrons have the same n, the same ℓ, and the same ml, then they are in the same orbital. the pauli exclusion principle states that no two identical fermions (a fancy word for electrons and other subatomic particles like electrons) may occupy the same quantum state in an atom simultaneously.

qualitative observation deals with data that can be observed with our senses: sight, smell, touch, taste, and hearing. they do not involve measurements or numbers. for instance, colors, shapes, and textures of objects are all qualitative observations.