Chapter 9, Problem 7P

However, the molecule we can encounter everyday continuously vibrates and interact with the surrounding causing its bond vector to vary slightly. According to a new spectroscopy analysis, the adjacent bond vectors was found to be A = 0.82i + 0.99j + 0.84k B = 1.09i + -1.01j + -0.97k What is the angle (in degrees) between the bonds based on this new data?

Given: Molybdenum has a BCC crystal structure, an atomic radius of 0.1363 nm, and an atomic weight of 95.64 g/mol. Required:   Calculate the theoretical density of molybdenum. Compare your calculated density to the experimentally measured density of 10.22 g/cm3.

Today I submitted this question and was given and answer but I cannot figure out where the 8 O came from in the solution without looking up how much oxygen weighs. Can you explain to me how this is solved with only the information in the question - If 112 g of silicon (Si) react completely with 64 g of oxygen (O) to form silica (SiO2), what is the atomic weight of silicon? I am supposed to solve it not using a periodic table and am very confused as to how to get to the answer in the book, 28.