Answer :
Electrons enter the 4s orbital before entering the 3d orbital because the 4s orbital is at a lower energy level. Hence option c is correct.
What is energy level?
Energy level is defined as when limited spatially, a bound quantum mechanical system or particle can only take on specific discrete energy values. In an atom, the small, positively charged nucleus is surrounded by smaller, negatively charged electrons. Energy levels resemble the rungs of a ladder in several ways.
According to a basic concept, electrons usually occupy the lowest energy orbitals first before moving on to the higher energy orbitals, hence they often enter the 4s orbital before entering the 3d orbital. The orbitals of the state with the lowest energy are determined using the (n+l) rule.
Thus, electrons enter the 4s orbital before entering the 3d orbital because the 4s orbital is at a lower energy level. Hence option c is correct.
To learn more about energy level, refer to the link below:
https://brainly.com/question/17396431
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So, a basic principle of the Universe is that particles WILL ALWAYS ENTER THE STATE OF LOWEST ENERGY. Because there are already so many electrons in the 3rd energy level, it jumps to the 4s level because there is less energy in the 4s level (because even though it's further out, there aren't that many electrons repelling it) — so it jumps to the place with lowest energy.
