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JEE MAIN_2026
04-04-26_S1
Question
Which of the following is correct set of 4 quantum numbers of $19^{\text {th }}$ electron in Chromium (Atomic number $=24)$ in accordance with Aufbau principle?
Select the correct option:
A
$n=3, l=2, m=+2, s=+\frac{1}{2}$
B
$n=3, l=2, m=-2, s=+\frac{1}{2}$
C
$n=4, l=1, m=0, s=+\frac{1}{2}$
D
$n=4, l=0, m=0, s=+\frac{1}{2}$
✓ Correct! Well done.
✗ Incorrect. Try again or view the solution.
Solution
$\mathrm{Cr} 1 s^2 2 s^2 2 p^6 3 s^2 3 p^6 4 s^1 3 d^5$
$\Rightarrow 19^{\text {th }} \mathrm{e}^{-}$belongs to 4 s subshell
$\mathrm{n}=4 ; \ell=0 ; \mathrm{m}=0 ; \mathrm{m}_{\mathrm{s}}=+\frac{1}{2}$ or $-\frac{1}{2}$
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