I have five less protons than the least massive metalloid in
the fourth period. Who am I?

You are the Cobalt

Explanation:

The least massive metalloid in the fourth period is Germanium, and it have 32 protons. If you have 5 less protons: 32 - 5 = 27 protons. The element with 27 protons is Cobalt

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.