Correct statements for an element with atomic number 9 are: A. There can be 5 electrons for which mₛ = +1/2 and 4 electrons for which mₛ = −1/2. B. There is only one electron in the p₂ orbital. C. The last electron goes to the orbital with n = 2 and l = 1. D. The sum of angular nodes of all the atomic orbitals is 1.

 

Question:

Correct statements for an element with atomic number 9 are:

A. There can be 5 electrons for which mₛ = +1/2 and 4 electrons for which mₛ = −1/2.
B. There is only one electron in the p₂ orbital.
C. The last electron goes to the orbital with n = 2 and l = 1.
D. The sum of angular nodes of all the atomic orbitals is 1.

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Short Solution (Text):

Step 1: Electronic configuration of Z = 9 (Fluorine):
1s² 2s² 2p⁵

• Option A:
  Fluorine has 9 electrons → 5 with spin +½, 4 with spin −½ ✅ Correct

• Option B:
  p₂ orbital? Actually, orbitals are labeled as pₓ, pᵧ, p𝓏. In 2p, 5 electrons → filling as per Hund’s rule. One orbital will have 2 electrons, two orbitals will have 2 & 1. So, yes, one orbital has 1 electron ✅ Correct

• Option C:
  Last electron goes into 2p orbital (n=2, l=1) ✅ Correct

• Option D:
  Angular nodes = l. For all orbitals of F:
  1s (0), 2s (0), 2p (1 each × 3 orbitals). Total angular nodes = 3 ❌ Not 1

✅ Final Answer: Correct Statements = A, B, C

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Conclusion – Video Solution: