Cause and Effect: Condensation of the nebula is caused by a. Heating of the universe
b. Supernova
c. Force of gravity
d. Solar winds

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.