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Structure of Atom question

2005 · Shift 0 · Q56
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Structure of Atom question

2005 · Shift 0 · Q56

JEE MainChemistryStructure of AtomMCQ+4 / −1
In a multi-electron atom, which of the following orbitals described by the three quantum members will have the same energy in the absence of magnetic and electric fields? (A) n = 1, l = 0, m = 0 (B) n = 2, l = 0, m = 0 (C) n = 2, l = 1, m = 1 (D) n = 3, l = 2, m = 1 (E) n = 3, l = 2, m = 0
  1. A
    (D) and (E)
  2. B
    (C) and (D)
  3. C
    (B) and (C)
  4. D
    (A) and (B)
View written solutionFree

Correct answer: A

  1. In a multi-electron atom, the energy of an orbital depends mainly on: n and ln \text{ and } ln and l because electron-electron repulsion and shielding remove the degeneracy that exists in hydrogen-like atoms.

  2. In the absence of magnetic and electric fields, the energy does not depend on the magnetic quantum number mmm.

  3. Therefore, orbitals having the same values of nnn and lll but different mmm will have the same energy.

  4. Now examine the given orbitals:

    • (A) n=1, l=0, m=0n=1,\ l=0,\ m=0n=1, l=0, m=0
    • (B) n=2, l=0, m=0n=2,\ l=0,\ m=0n=2, l=0, m=0
    • (C) n=2, l=1, m=1n=2,\ l=1,\ m=1n=2, l=1, m=1
    • (D) n=3, l=2, m=1n=3,\ l=2,\ m=1n=3, l=2, m=1
    • (E) n=3, l=2, m=0n=3,\ l=2,\ m=0n=3, l=2, m=0
  5. Compare their nnn and lll values:

    • (D): n=3, l=2n=3,\ l=2n=3, l=2
    • (E): n=3, l=2n=3,\ l=2n=3, l=2

    These differ only in mmm, so they have the same energy.

  6. Check other pairs:

    • (B) and (C): same n=2n=2n=2, but l=0l=0l=0 and l=1l=1l=1 different ⇒\Rightarrow⇒ different energy
    • (C) and (D): different nnn and lll ⇒\Rightarrow⇒ different energy
    • (A) and (B): different nnn ⇒\Rightarrow⇒ different energy
  7. Hence the correct option is: A: (D) and (E)\boxed{\text{A: (D) and (E)}}A: (D) and (E)​

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