a simple cubic stucture consists of a single atom in the center of the cube. the lattice constant is a0. determine the volume denstiy of atoms and the surface density of atoms in the (110) plane

In a laboratory, 1.55mg of an organic compound containing carbon, hydrogen, and oxygen is burned for analysis. this combustion resulted in the formation of 1.45mg of carbon dioxide and .89 mg of water. what is the empirical formula for this compound?

I'm learning about the periodic tables and what each subject's configuration is. for example, hydrogen is 1s^1, but i don't understand how you get that. can someone me understand how to figure out how to figure this out? sorry if the question makes no sense, but it would really a lot if you could me understand! you so much if you can!

State one important difference between a physical change and a chemical change?