Question

Which of the following is not possible ?

• A. \(n=3, l=0, m=0\)
• B. \(n=3, l=1, m=-1\)
• C. \(n=2, l=0, m=-1\)
• D. \(n=2, l=1, m=0\)

Hint:

For \(l=0\) (s-orbital), magnetic quantum number is always \(m=0\). No exceptions.

Answer 1

The Correct Option is C

Concept: Quantum Numbers
• Principal quantum number: \( n = 1, 2, 3, \dots \)
• Azimuthal quantum number: \( l = 0 \text{ to } (n-1) \)
• Magnetic quantum number: \( m = -l \text{ to } +l \)

Step 1: Check each option (A) \(n=3, l=0, m=0\) Allowed since \(l=0 \Rightarrow m=0\) (B) \(n=3, l=1, m=-1\) Allowed since \(m = -1,0,+1\) (C) \(n=2, l=0, m=-1\) Here \(l=0\), so: \[ m = 0 \text{ only} \] But given \(m=-1\) → not allowed (D) \(n=2, l=1, m=0\) Allowed since \(m = -1,0,+1\) Final Answer: C