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Question 840013
JEE Chemistry · Hard

Periodic Table and Periodicity: Mixed MCQ

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MixedHardQuestion 840013

Question

The effective nuclear charge (Zeff) experienced by valence electrons in Na is approximately:
  1. A
    2.5
    Correct
  2. B
    11
  3. C
    8
  4. D
    1

Correct answer

2.5

Explanation

Slater's rules for Na (3s electron): screening from (2s,2p) × 0.85 = 8 × 0.85 = 6.8; from (1s,2s) already counted in 2s group; from core 2 × 1.0 = 2.0. Total screening = 8.8. Zeff = 11 − 8.8 = 2.2. The approximate value using simple rules is ~2.2–2.5.

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