Two students made the Lewis dot diagrams of NH3. The diagrams are as shown. Which student drew the correct Lewis dot diagram?
1) Only Student A
2) Only Student B
3) Both Student A and Student B
4) Neither Student A nor Student B

What happens to energy in an open system?

Compare and contrast physical changes with chemical changes.

Skills of homo sapiens were found an excavation. the skulls were preserved because the bodies were frozen. so, these fossils are (blank) fossils. the image shows the evolution of skulls beginning 2 to 3 million years ago. based on the image, modern human skulls(blank) ape skulls.