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🧪 Chemistry  ·  Structure of Atom  ·  NEET & JEE

Which of the following sets of quantum numbers is allowed for an electron in an atom?

Answer: n=3, l=2, m l =-2, m s =+1/2.

  • A n=2, l=2, m<sub>l</sub>=0, m<sub>s</sub>=+1/2
  • B n=1, l=1, m<sub>l</sub>=0, m<sub>s</sub>=-1/2
  • C n=3, l=2, m<sub>l</sub>=-2, m<sub>s</sub>=+1/2
  • D n=2, l=0, m<sub>l</sub>=1, m<sub>s</sub>=+1/2

Correct answer: C. n=3, l=2, m<sub>l</sub>=-2, m<sub>s</sub>=+1/2

Explanation: For n = 3, l can be 0,1,2; with l = 2, m<sub>l</sub> can be -2, so this set is valid. The others violate the rule that l < n and that m<sub>l</sub> ranges from -l to +l.

NK (n=1)L (n=2)M (n=3)

Bohr's model: electrons occupy fixed circular shells (K, L, M) around the nucleus, with each shell holding up to 2n2 electrons.

Concept context

Explore how electrons are arranged inside an atom. Covers Bohr's model, quantum numbers, Heisenberg's uncertainty principle, shapes of s, p, d orbitals, and electronic configuration rules.

Read the full Structure of Atom notes →