Which of the following occurs when an electron moves from a higher energy shell to a lower energy shell?

it's c. elements are placed in rows based on how may valencies electrons have.

acid rain does not usually kill trees directly. instead, it is more likely to weaken the trees by damaging their leaves, limiting the nutrients available to them, or poisoning them with toxic substances slowly released from the soil. the main atmospheric pollutants that affect trees are nitrates and sulphates.