Question:
Observe the elements from H (Z=1) to Ca (Z=20). How many elements have no unpaired electrons in their ground state?
Observe the elements from H (Z=1) to Ca (Z=20). How many elements have no unpaired electrons in their ground state?
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Look at electron configurations.
Fully filled shells (s^2, p^6) have no unpaired electrons.
Check up to Z = 20 carefully.
Paired electrons → diamagnetic.
Fully filled shells (s^2, p^6) have no unpaired electrons.
Check up to Z = 20 carefully.
Paired electrons → diamagnetic.
Updated On: Oct 27, 2025
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- 9
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The Correct Option is A
Solution and Explanation
• Elements with all electrons paired: He, Be, Ne, Mg, Ar, Ca.
• Count = 6.
• Count = 6.
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