substance a decomposes at a rate proportional to the amount of a present. it is found that 12 lb of a will reduce to 6 lb in 4.2 hr. after how many hours will there be only 1 lb left?

In the image, layer a is the topmost layer. layer c contains fossils from the precambrian era. layer b contains dinosaur fossils, and layer a contains fossils of mammals. which two statements are supported by this evidence? 1. mammals lived before the precambrian era. 2. dinosaurs and mammals existed in the precambrian era. 3. dinosaurs evolved after precambrian organisms. 4. precambrian organisms evolved after dinosaurs. 5. precambrian organisms were the first life-forms to become fossilized, according to this sample.

What are the three stages of volcanic activity? a. active, magma, lava c. extinct, eruption, explosive b. eruption, quiet, explosive d. active, dormant, extinct

Which of the following does the reading test of the sat ask you to do ?