NCERT · Class 11 · Chemistry · Structure of AtomAccording to Aufbau principle, which orbital is filled first among $4s$ and $3d$?
Step-by-Step Solution
Using the $(n+l)$ rule: for $4s$, $n+l = 4+0 = 4$; for $3d$, $n+l = 3+2 = 5$. Since $4s$ has lower $(n+l)$, it is filled before $3d$.
Detailed Options Breakdown
Option : $3d$ orbital
Incorrect choice. This distractor represents a common misunderstanding of the core principles of Structure of Atom.
Option 1: $4s$ orbital (Correct Answer)
Correct choice. Refer to the step-by-step verified solution guidelines above for details.
Option 2: Both are filled simultaneously
Incorrect choice. This distractor represents a common misunderstanding of the core principles of Structure of Atom.
Option 3: Depends on the atomic charge
Incorrect choice. This distractor represents a common misunderstanding of the core principles of Structure of Atom.
💡 Study Guide: This question tests core syllabus concepts from Structure of Atom. For formulas, key summaries, and mock exam reference guides, read the full Structure of Atom Revision Notes.