Answer:
A = 2s²
B = 2p⁴
or 2s² 2p⁴
Step-by-step explanation:
Oxygen:
It is the eighth element of periodic table. It is present in group sixteen and second period of periodic table. It has six valance electrons. It is also called chalcogen because it is ore forming element. its atomic number is 8.
Electronic configuration:
O₈ = 1s² 2s² 2p⁴
The two electrons in 1s shell represent the core electrons while the six electrons in second shell are valance electrons.
Valance shell electronic configuration :
2s² 2p⁴