Answer:
part 1 is from the article
Explanation:
There are 7 valence electrons in the atom :)
Answer:
To check if it's properly cleaned.
Explanation:
When you finish using a microscope, you have to take out all your samples you were using and make sure it is completely clean so that no further contamination affects future sample analysis.
Also when you begin to use it, make sure it is clean so that when you analyze your sample(s) are free from other unexpected agents.
