2. Which of the most abundant elements in Earth's crust are nonmetals?

Oxygen

Explanation:

The thing is, The most abundant of the other nonmetals in the Earth's crust is oxygen which is the single most abundant element in the Earth's crust

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.

air quality

poor drinking water

and heavy polution

can lead to poor health