What is the difference between a molecular formula and a molecular model?

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.

In what environment would mineral formation caused by high pressures and high temperatures most likely occur?

Can someone me with 3 and 4 plz. this is for masteries test.