Based on the graph, determine the amount of u-238 that would remain after 4.5 billion years, if the original sample contained 6 grams of pure u-238. a) 0.75 grams b) 3 grams c) 6 grams d) 12 grams

Which of the following is a feature of all cells? o a. all cells have a nucleus. o b. all cells have dna for at least part of their life cycle. het . o c. all cells are spheres. o d. all cells have a rigid cell wall.