A. Ne, 4p2
B. Ar, 4s2
C. Ne, 4s2
D. Kr,4p2
¨ The correct electronic configuration of a calcium (Ca) atom is 1s2 2s2 2p6 3s2 3p6 4s2.
¨ This can be represented as [Ar] 4s2, where [Ar] represents the electron configuration of the noble gas argon, which has 18 electrons.
¨ This is because the electronic configuration of calcium (Z=20) follows the Aufbau principle, which states that electrons fill lower energy levels first before filling higher energy levels.
¨ In the case of calcium, the first 18 electrons fill the lower energy levels up to the argon configuration ([Ar]), leaving the remaining two electrons to fill the 4s orbital.
Submitted by :- Jamil Ahmed