Following a volcanic eruption which event is usualy the last one to be observed

A. grasses begin to grow in soil with organic matter

B. tress begin to grow in thick rich soil

C. mosses begin to grow in thin rocky soil

D. lichens begin to cover bare rock

It would be B. because that comes last.

Explanation:

Whenever a volcano erupts, it puts a layer of rock over everything. Basically, over years and years, lichens will start growing and breaking down the rock. A bunch of years later, mosses will begin to grow in the "soil" that the lichens broke down. When the rocky dirt becomes actual dirt, grasses will start to grow. After that shrubs, and then trees.

Hope this helped! :)

quartz

explanation:

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.