Answer:
A control group is a set standard so that comparisons can be made to see what your experiment did. The experimental group is the group that has been changed. A control group also allows you to determine your variables.
Explanation:
Answer:
D. The Earth system essentially contains a fixed amount of chemical elements that cycle continuously throughout the system.
D I think
I have no idea why just makes a lot of sence
No you should tear down all of the power plants because it is a power source that can still go on without something attached to it
1)Strength of the sun
2)Changes of the earths orbit
3) Changes in the orientation of the axis of the rotation
4)Quantity of the greenhouse gases in the atmosphere
5)Carbon dioxide content of the oceans
