Answer:
The crust is thinner and less dense than the mantle.
Soil erosion can be caused by acid rain, mining, and water
Student 2 is correct and the same group of worms should be used.
<h3>What is an experiment?</h3>
An experiment is the process by which we establish cause and effect relationships in science. The control variable are those that must be kept the same in the experiment.
We know that the experiment will only be valid if the research is carried out with the same group of worms. If different groups of worms are used, other factors may account for the results obtained.
Thus student 2 is correct and the same group of worms should be used.
Learn more about experiment:brainly.com/question/11256472?
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The levels of an environment to be organized are populations,species,community, and the ecosystem
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