1. ans: It is generated from source of layers , migrates upward by displacing water and is trapped by overlying layers that will not allow hydrocarbons to further upwards .
The reason why is a few things, first, they have to make sure that the organism is related, and that they can see that. They don't wanna assign a bird as an insect on accident, so they do tests and then determine. Second, the more factors the better, if you consider all the species in the world, and what makes them different from eachother you would have a very long list. And that is it.
I hope this helps. If you need clarity or anything just ask.
Acid rain can be very harmful, mildly harmful, or not harmful at all. It mainly depends on the density of the rain, and how bad the current air pollution in the area is. Also, it depends on how often the area gets acid rain. The first few times an area gets acid rain, it's nearly harmless. Then, the next few it can be very dangerous, but eventually gets weaker over time. More air polluted areas are more likely to get much more harmful acid rain.
Summary: Acid rain is usually mildly harmful, mostly only harmful to infrastructures.<span />
Not sure if you still need the answer but its number Three, they are the decomposers in many ecosystems
They run up a tree and steal them from all the birds nests then swallow them