Can someone help me out please? Silicone has three naturally occurring isotopes. They have mass numbers of 28, 29, 30. If the atomic mass of silicone is 28.086, which is the most abundant? Explain

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.

Jessica is traveling from miami, florida, to chicago, illinois. using the map, tell one way the land will change during the second half of her trip.

What layer of the atmosphere is directly above the troposphere?