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Which element has the electron arrangement 2, 8, 1?
ASodium (Na, atomic number 11)
BMagnesium (Mg, atomic number 12)
CLithium (Li, atomic number 3)
DPotassium (K, atomic number 19)
Answer & Solution
Correct answer: A. Sodium (Na, atomic number 11)
1. Total electrons = 2 + 8 + 1 = 11.
2. In a neutral atom, electron count equals proton count.
3. Proton count 11 means atomic number 11.
4. Element with Z = 11 is sodium.
_Source: Selina Concise Chemistry Class 8, Ch on Structure of Atom (Mistral OCR'd PDF), section on electron arrangement_
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