See explanation below.
Work Step by Step
The electron removed in Group 2A(2) atoms is from the outer level s orbital, whereas in Group 3A(13) atoms the electron is from the outer level p orbital. For example, the electron configuration for Be is 1s2s2 and for B is 1s2s2p1. It is easier to remove the p electron of B than the s electron of Be, because the energy of a p-orbital is slightly higher than that of the s orbital from the same level. Even though the atomic size decreases from increasing Zeff, the IE decreases from 2A(2) to 3A(13).