JEE Main ¡ 2020 ¡ Shift-IeasyATOM-125

In the sixth period, the orbitals that are filled are:

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

Question

In the sixth period, the orbitals that are filled are:

Options
  1. a

    6s,4f,5d,6p6s, 4f, 5d, 6p

    ✓
  2. b

    6s,5d,5f,6p6s, 5d, 5f, 6p

  3. c

    6s,5f,6d,6p6s, 5f, 6d, 6p

  4. d

    6s,6p,6d,6f6s, 6p, 6d, 6f

Correct Answera

6s,4f,5d,6p6s, 4f, 5d, 6p

Detailed Solution

🧠 The Periodic Fill Sequence The sequence of orbitals filled in any period follows the (n+l)(n+l) rule. A period always starts with an ss-orbital and usually ends with a pp-orbital.

🗺️ The 6th Period Audit For n=6n=6:

  1. Start: 6s6s (n+l=6n+l = 6).
  2. The f-block: 4f4f (n+l=4+3=7n+l = 4+3=7).
  3. The d-block: 5d5d (n+l=5+2=7n+l = 5+2=7). (Note: 4f4f fills before 5d5d due to lower nn).
  4. End: 6p6p (n+l=6+1=7n+l = 6+1=7). Correct Sequence: 6s,4f,5d,6p6s, 4f, 5d, 6p.

⚡ The (n+l)(n+l) Rule Orbitals are filled in order of increasing (n+l)(n+l). 6s(6)→4f(7)→5d(7)→6p(7)6s(6) \to 4f(7) \to 5d(7) \to 6p(7). Within the 77-ties, the lowest nn fills first.

⚠️ Common Traps Don't include 5f5f or 6d6d. Those belong to the 7th7^{\text{th}} period.

Answer: (a)\boxed{\text{Answer: (a)}}

Practice this question with progress tracking

Want timed practice with adaptive difficulty? Solve this question (and hundreds more from Structure of Atom) inside The Crucible, our adaptive practice platform.