Why do geologists think Earth's core contains mostly iron?
A. The entire core is a solid mass.
B. The crust also contains mostly iron.
C. Comets contain more iron than Earth's crust does.
D. Iron is the lightest element.

Which of the following examples can cause gene flow between populations? a.an increase in predators to a population of zebra b.a volcanic eruption that kills half of a population of mice c.bird droppings that contain seeds from a different location d.a person that sprays a toxin on a group of mosquitoes

Which of the following is the function of the nociceptors? a. detecting odors in the nose b. detecting painful stimuli c. detecting central body temperature d. detecting touch and pressure

Astar that has expanded and cooled?