What are the evidence of continental drift

How to convert a density of 0.791g/cm3 to lb/ft3

Helium decays to form lithium. which equation correctly describes this decay?

Acertain atom has 22 protons and 19 electrons. this atom loses an electron. the net charge on the atom is now 4+1+01-4-. if this same atom with 22 protons and 19 electrons were to gain 3 electrons, the net charge on the atom would be 3+2+02-3-.