Chemistry - PERIODIC TABLE Question with Solution | TestHub

First ionization enthalpy (IE₁) of B, Al, Ga are 801, 577 and 579 kJ/mol respectively. 

As decrease in first ionization enthalpy is much larger from B to Al. $∆{\mathrm{IE}}_1$ of B and Al is greater than $∆{\mathrm{IE}}_1$ of Al and Ga. So, the statement I is correct.

This is due to completely filled d-orbitals in Ga and d-electron have low screening effect to compensate the increase in nuclear charge. So, The statement II is also correct.

Hence, the correct option is B.