What is the electron configuration for beryllium (atomic number = 4)?
А
B
1s22s
2.
2s22p
2

What happened in 2012 and how does it illustrate the importance of understanding the sun and how it works?

What type of electromagnetic waves does the human eye see as the colors red blue or green a visible light waves b radio waves c infrared waves d microwaves

What is the average rate of the reaction between 10 and 20 s?