Answer :
Final answer:
In a polyelectronic atom, the subshell combinations that are closest in energy after being filled are the 4s and 3d subshells, due to electron-electron interactions and shielding effects. Therefore, the correct answer is Option (d) 4s and 3d.
Explanation:
Subshells fill in a polyelectronic atom in accordance with energy levels that are determined by the primary quantum number (n) and the angular momentum quantum number (l) as more electrons are added. The Aufbau principle states that orbitals fill in the following order: the 4s subshell fills before the 3d subshell. Due to electron-electron interactions and shielding effects, the energy of the 3d electrons is actually somewhat lower than the energy of the 4s electrons once the 4s has been filled. Since both subshells have the closest energy levels once both are filled in atoms with more than 20 electrons, (d) 4s and 3d is the correct response.
The sub shell combinations which is closest in energy in the typical polyelectron atom is 4s and 3d.
The sub shell combinations that are closest in energy in a typical polyelectron atom are those that are in the same principal energy level and have the same value of (n+l) quantum number. According to this criterion, the closest in energy sub shell combinations are:
(a) 4s and 4p, since n+l=4+0=4 for both sub shells
(c) 3d and 3s, since n+l=3+2=5 for both sub shells
(d) 4s and 3d, since n+l=4+0=4 for 4s and n+l=3+2=5 for 3d, which are relatively close.
Therefore, the correct answer is (d) 4s and 3d.
To learn more about principal energy level : https://brainly.com/question/28104772
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