Answer
a) Ga and Si
d) Tl and Sn
e) B and Si
Work Step by Step
The periodic trend is not sufficient enough to determine which has the higher first ionization energy for these pairs of elements because each of these pairs are located diagonally from each other on the periodic table. Periodic trends often move from right to left across periods. For example, as one moves to the right, ionization energy increases. Likewise, as one moves down a group of elements, the ionization energy decreases. It's therefore difficult to predict ionization for elements that are located diagonally from one another.
