What dose the atomic number of an element represent

Water's surface tension and heat storage capacity are accounted for by its a) orbitals b) weight c) hydrogen bonds d) mass e) size

What is the molarity of the solution produced when 145 g of nacl is dissolved in sufficient water to prepare 2.75 l of solution?

Asuspension of yeast cells is being grown under anaerobic conditions such that glucose is degraded to ethanol and carbon dioxide. if one wishes to follow this process by monitoring the release of 14co2, at which positions in the glucose molecule would the 14c label need to be incorporated?