The following is not an organic compound? a) penicillin. b) urea. c) oxalic acid d) plaster of paris

D. Plaster of Paris

It's calcium sulfate hemihydrate, which hardens when moistened to form gypsum, calcium sulfate dihydrate.

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.