Ionization Trend: First ionization energy will increase left to right across a period and increase bottom to top of a family (column).
A) Sr, Be, Mg are all in column 2 of the periodic table. Based on the first ionization rule above, from increasing to decreasing energy, the order is: Be, Mg, Sr
B) Bi, Cs, Ba are all in the same row of the periodic table. Based on the first ionization rule above, from increasing to decreasing energy, the order is: Bi, Ba, Cs
C) Same rule as above. Order is: Na, Al, S