Also what is the arrow a pointing to?

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. : )

4. absorption has the highest risk of overdose due to increased potency. a. rectal b. oral c. transdermal d. intranasal

Calculate the mass of 0.750 mol of the following substance. na3po4.