JEE Main · 2019 · Shift-IIhardATOM-137

Which combination of statements is true regarding atomic orbitals? (A) An electron in an orbital of high angular…

Structure of Atom · Class 11 · JEE Main Previous Year Question

Question

Which combination of statements is true regarding atomic orbitals?

(A) An electron in an orbital of high angular momentum stays away from the nucleus than an electron in the orbital of lower angular momentum.

(B) For a given value of the principal quantum number, the size of the orbit is inversely proportional to the azimuthal quantum number.

(C) According to wave mechanics, ground state angular momentum = h/2πh/2\pi.

(D) The plot of ψ\psi vs rr for various azimuthal quantum numbers shows peak shifting towards higher rr value.

Options
  1. a

    (B), (C)

  2. b

    (A), (B)

  3. c

    (A), (C)

  4. d

    (A), (D)

Correct Answerd

(A), (D)

Detailed Solution

🧠 The penetration Paradox High angular momentum (ll) means the electron is rotating more "outwardly," making it less effective at "penetrating" through the core towards the nucleus.

🗺️ Statement Verification

  • (A): TRUE. Orbitals with lower ll (like s) are more "penetrating." Electrons with high ll (like d or f) are "shielded" and stay further away from the nucleus on average.
  • (B): FALSE. The size is primarily dictated by nn.
  • (C): FALSE. Wave mechanics (Schrödinger) says ground state (1s1s) angular momentum is zero (l=0l=0). h/2πh/2\pi is the Bohr model value.
  • (D): TRUE. As ll increases for a fixed nn, the main probability peak shifts further outward from the nucleus.

Correct Combo: (A) and (D).

The "s < p < d" Shielding Think of 's' electrons as the "bodyguards" of the nucleus. They stay closest. 'd' and 'f' electrons are like the patrons further back in the crowd.

⚠️ Common Traps Forgetting that Bohr and Schrödinger disagree on the 1s angular momentum. Schrödinger's L=0L=0 is the wave mechanics reality.

Answer: (d)\boxed{\text{Answer: (d)}}

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