What arrangements if electrons in an atom did Niels Bohr propose?

What does x represent in the formula for the compound xcl4?

Explain that newton first law,second law and third law of motion?

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.