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# For the energy levels in an atom which one of the following statements is correct?A. The $4s$ sub-energy level is at higher energy than the $3d$ sub-energy level.B. The $M$-energy level can have a maximum of $32$ electrons.C. The second principal energy level can have four orbitals and contain maximum of $8$D. The $\mathop 5\nolimits^{th}$main energy level can have a maximum of $50$ electrons.

Last updated date: 16th Jun 2024
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Hint:Energy levels (also called electron shells) are fixed distances from the nucleus of an atom where electrons may be found. Electrons are tiny, negatively charged particles in an atom that move around the positive nucleus at the center.

Energy of the orbits is decided by $(n + l)$ rule.
$n$ is called principal quantum number.$n = (1,2,3,4.....)$
$l$ is known as azimuthal quantum number. $l = (0,1,2.....n - 1)$
Solve the question step by step-
$4s$; $n = 4$ and for $s$, $l = 0$
Energy level of $4s$ is decided by $(n + l)$ rule.
So, energy level is $4 + 0 \Rightarrow 4$
For $3d$; $n = 3$ and $l = 2$
Energy level is $(n + l) \Rightarrow (3 + 2) \Rightarrow 5$
$3d$ is at a higher energy level than $4s$.
Hence, the statement is false.
B)$M$-energy level, $n = 3$.
Maximum electron capacity is calculated by $2{n^2} = 2 \times 9 = 18$
Hence, the statement is false.
C) The second principal energy level can have four orbitals, $s,p,d,f$ and $n = 2$
Maximum number of electrons is $2{n^2} = 2 \times 4 = 8$
Hence, the statement is true
D) The $5th$ energy level can have a maximum of $32$ electrons.
Hence, the statement is false.
Thus,the correct option is (C).

Note:There are four main concepts that you must remember in electron configuration. They are energy levels, sublevel, orbitals, and number of electrons per sublevel. Bohr proposed that electrons inside an atom occupy only certain allowed orbitals with a specific energy. In other words, the energy of an electron in an atom is not continuous, but 'quantized.' The energies corresponding to each of the allowed orbitals are called energy levels.