Respuesta :
Answer:
b.their electrons are assigned to s and p orbitals only.
Explanation:
Electron configuration of He, B and Al the elements that lie in the first, second and third period of the periodic table respectively as follows:
He: 1s²
B: [He] 2s² 2p¹
Al: [Ne] 3s² 3p¹
Ga: [Ar] 3d¹⁰ 4s² 4p¹
In Ga, element ling in the 4th period, electrons enter the s, p and d orbitals. So before assigning electrons to the p orbitals it is important to ensure that the d orbital is either partially or fully filled.