If an isotope has a half-life of 4 billion years, then in 4 billion years what will happen?
a. all of the original amount will have decayed
b. half of the original amount will still be present
c. a quarter of the original amount will still be present
d. all of the original amount will still be present

Put the following steps of the convection process in the correct order. 1. gravity pulls cooler matter downward. 2. the matter expands and decreases in density. 3. an up-and-down flow of matter produces a convection current. 4. matter is heated. 5. warmed matter is forced upward. question 2 options: a) 4, 2, 5, 1, 3 b) 2, 4, 3, 1, 5 c) 3, 2, 5, 4, 1 d) 1, 4, 2, 5, 3

Which blood cell spend most of their time in the lymphatic system?

What would happen if the krill were removed from the food web