What is a well-ordered array and what do they have to do with atoms?

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.

colorless gas, exhibiting a blue glow when placed in an electric field

b) solid

its a type of rock