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Why is an elements atomic mass not listed as a whole number on the periodic table

Schrodinger and heisenberg developed an alternate theory about atomic nature that contradicted some of bohr's model of the atom. how do changes resulting from new technology and evidence affect the reputation of the atomic theory?

Before it was launched, a helium-filled balloon had a pressure of 201 kpa at a temperature of 27°c. at an altitude of 15,000 m, the pressure had decreased to 2.5 kpa and the temperature had dropped to -14 °c. the volume of the balloon increased to 59.3 m3. what is the original volume of the balloon? 13 m3 0.85 m3 0.077 m3 1.17 m3