7. Tellurium consists of 3 common isotopes. Half of tellurium atoms have a mass of 127. and another 0.45 of tellurium atoms weigh 128. What is the mass of the remaining isotope? The atomic mass of tellurium is 127.5

Iknow the answer is a but i don't know why

What is the relation between concentration of reactants and the rate of chemical reaction?

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.