Humans are most abundant during which geological era? Cenozoic
Precambrian
Palcozoic
Mesozoic

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.

Imagine that you push on a large rock. at what point does your effort change the rock’s mechanical energy?

Which statement explains why the bonds between non metals tend to be covalent? the bonds are found to be nondirectional they have large differences in electronegativity they have small differences in electronegativity they have ions that produce an electrostatic pull