Which element has an equal number of electron pairs and of unpaired electrons within orbitals of principal quantum number 2?

Alarge marble is dropped in a graduated cylinder with 35ml of water in it.the water level increases to 49ml.what is the volume of the marble

The image shows a process that releases nuclear energy which statement best identifies the process shown the process must be fusion because energy is released the process must be fusion because of have your nucleus formed a smaller nuclei the process must be fission because a large nucleus breaks into smaller nuclei the process must be fission because neutrons are formed

Use the periodic table to determine the electron configuration of dysprosium (dy) and americium (am) in noble-gas notation.