Answer:
50% is filled
Step-by-step explanation:
The electron configuration of carbon (C) is written as C 1s² 2s² 2p². It is evident from the electron configuration of carbon, the first shell or first energy level is completely filled with two electrons. But in a bond, carbon changes its configuration to 1s²2s¹2p³.
One electron from the 2p orbital jumps up to the 3p orbital. Thus, carbon gives a sp³ hybridization and second energy level is half filled or 50% filled.