The mass of an atom may be determined by adding the masses of the protons and neutrons in the nucleus. why is it unnecessary to include the electrons when determining the mass of an atom?

The solubility of barium nitrate is 9.02 g/100 g h2o at 20°c. a 15.2 g sample of barium nitrate is added to 200.0 g of water at 20°c. is the solution saturated, unsaturated, or supersaturated? a. unsaturated b. saturated c. supersaturated