For elements with atomic numbers 34–38, a student records the following qualitative observations from a plot of first-ionization energy versus atomic number:
• A pronounced maximum occurs at Z=36.
• The value at Z=37 is the lowest within this range.
• The values at Z=34 and Z=35 are intermediate and increase steadily.
Based on these observations, which atomic number in this set corresponds to an alkali-metal element?
a) 36
b) 35
c) 37
d) 38