A well designed experiment should have which of the following characteristics

What happens to the composition of an atom to cause it to become positively or negatively charged?

Feedback is given with little or no reservation 1.supportive 2.high-monitoring 3.positive 4.low-monitoring ?

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.