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Structure of the Atom — Science STD 9 — Question

Gujarat BoardEnglish MediumSTD 9ScienceStructure of the Atom2 Marks
Question
Helium atom has $2$ electrons in its valence shell but its valency is not $2$, Explain.
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Answer

Helium atom has $2$ electrons in its outermost shell and its duplet is complete. Hence the valency of helium atom is zero. It has no propensity to give or take electrons.

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