Which substance has Delta. Hf defined as 0 kJ/mol? H2O (s) Ne (l) F2 (g) CO2 (g)

Asample of radium-226 will decay 1/4 of its original amount after 3200years. what is the half-life of radium-226?

How do scientists think that gravity affected the formation of our solar system?

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.