What is the name of MnO3

1) how many electrons are in each energy level of the following elements? a. he b. na c. na d. ne 2) how many valence electrons are percent in the following atoms? a. s b. mg c. be d. cl 3) which of the following elements are stable as atoms? a. he b. o c. cl d. ar if you are able to provide the work as to how you got the answers that would be greatly appreciated. : )

Iknow #2 is d. i just need to know why

1) these are barrel shaped microtubules in most animal cells, that organize the spindles during cell division