How many molecules are in 2.14 mol co?

Which of the following statements is true? a. elements in the last period are radioactive. b. atomic weight is the same as atomic mass. c. elements in the same group have the same number of electron shells. d. atomic number equals the number of neutrons in the nucleus of an atom.

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

What substance has a mass of 9.5g and volume of 2.1cm^3