What makes modern chemistry different from alchemy and other ancient chemical practices of pre-modern humans?

Alchemy was based more on experimentation and had little basis in science. Chemistry utilizes both experimentation and scientific practices. Modern chemistry basically relies on scientific theories and experimental results, but the alchemy was a blend of myths, religion, magic, astrology, philosophy, and spirituality.

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.