JEE Main · 2023 · 24 Jan 2023 · Shift 2 · Atomic Structure

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The number of s-electrons present in an ion with 55 protons in its unipositive state is
  1. (A)8
  2. (B)9
  3. (C)12
  4. (D)10✓ Correct

Answer: (D)

Solution

An atom with protons is caesium, and removing one electron for the unipositive ion gives the closed xenon configuration . Counting the electrons in the sub-shells of this arrangement, the , , , and orbitals each hold two. Their sum is ten -electrons.

JEE Main · 2023 · 24 Jan 2023 · Shift 2 · Single correct option

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