A compound is a substance that consists of 2 or more elements chemically combined in a fixed proportion.
Compounds can be broken down ijt0 simple substances by chemical means but, elements cannot.
Answer:
biggest problem with mainstream renewable energy is intermittency.
Erosion? As time passes, the continents move? Some crumble? I don't know but I tried
Answer:
C. because the 4s orbital is at a lower energy level
I believe it's answer #3. Logically, at least.
You can test #1 through trial and error.
You can experiment #2 also through trial and error.
You cannot test #3 through trial and error, because that would be catastrophic.
You can test #4 through a survey and individual study and data collection.
