Gas is squeezed into a small container is it compressibility or heat of combustion

Squeezing a gas into a small container is an example of compressibility (a physical change).

You measure the heat of combustion (a chemical change) when something burns.

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.