Chemistry - PERIODIC TABLE Question with Solution | TestHub

Electronic configuration of Be$=1{\mathrm{s}}^2\mathrm{ }2{\mathrm{s}}^2$
Electronic configuration of B$=1{\mathrm{s}}^2\mathrm{ }2{\mathrm{s}}^2\mathrm{ }2{\mathrm{p}}^1$
Due to full-filled configuration of Beryllium, it has higher first ionization energy.
Effective nuclear charge
${\mathrm{Z}}_{\mathrm{e}\mathrm{f}\mathrm{f}}$of Be$=4-\mathrm{\sigma }=4-\left(2\times 0.85+0.35\times 1\right)=2.05$
${\mathrm{Z}}_{\mathrm{e}\mathrm{f}\mathrm{f}}$of B$=5-\mathrm{\sigma }=5-\left(2\times 0.85+0.35\times 2\right)=2.6$
$\therefore {\mathrm{Z}}_{\mathrm{e}\mathrm{f}\mathrm{f}}$of B >${\mathrm{Z}}_{\mathrm{e}\mathrm{f}\mathrm{f}}$of Be