Despite the fact that the solubility rules have the word "rules" in the title, there are several exceptions to each that don't make much sense. The instance above shows a two of them.

beta decay is the answer

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.