Which electron in an atom (Z=17) is the most shielded from nuclear charge?
A. an electron in the 2s B. an electron in the 3p
C. an electron in the 3d D. an electron in the 1s

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