Question

which is the electron configuration for boron?
1s²2s³
1s²2s²3s¹
1s¹2s²2p²
1s²2s²2p¹

Explanation:

Boron has an atomic number of 5. Electrons fill orbitals in the order of increasing energy. The 1s orbital fills first (holding 2 electrons), then the 2s orbital (holding 2 electrons), and then the 2p orbital starts to fill. For boron with 5 electrons, the electron - configuration is 1s²2s²2p¹.

Answer:

1s²2s²2p¹ (the last option)