The atomic number of an element 'X' is 11.
Generated by claude-sonnet-4-6 · 2026-06-15 06:50 · grounding rag
Model Answer
(i) Element X has atomic number 11 (Sodium, Na).
Electronic configuration: 2, 8, 1
Valency = 1 (it has 1 electron in the outermost shell, which it loses to attain a stable octet).
(ii) Sodium forms the oxide Na₂O (sodium oxide).
Its nature is basic (metals combine with oxygen to form basic oxides).
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Explanation
- For (i), write the shell-wise distribution (K=2, L=8, M=1) and state valency as the number of electrons lost/gained to complete the octet.
- For (ii), since Na is monovalent (Na⁺) and oxygen is divalent (O²⁻), the formula is Na₂O. Examiners expect the word "basic" as the nature — remember: metal oxides are basic oxides (except amphoteric ones like Al₂O₃, ZnO).