I need this to be answered and pls don’t guess I really don’t know density

Earth's atmosphere is unique among the planets and is able to support life because it contains a large amount of a) oxygen b) helium c) methane d) carbon dioxide

Scientists observed a rock stratum and discovered some fossils. the image shows the fossils they discovered. what can you interpret from the image? an illustration showing layers rock with fossils embedded in some rock layers1. the dinosaur and the mammoth existed after the trilobites.2. the dinosaur and the armored fish existed before the trilobites.3. the trilobites and the armored fish died before the dinosaur.4. the trilobites and the armored fish were born after the dinosaur.5. the early mammoth is older than the trilobites.

How are 3-d printers useful in studying evolution? a. to color the fossils of organisms b. to create clones of extinct organisms c. to create replicas of fossils d. to prepare paper cutouts of organisms e. to study the composition of fossils