MCQ practice · SSC Chemistry Board questions · Chapter 5: Chemical Bond
When it forms an ion, potassium reaches the configuration of which element?
Think it through first, then pick an option.
- a Ar
- b Cr
- c Kr
- d Sr
Answer and explanation
Correct answer: a Ar
K (2, 8, 8, 1) gives one electron to become K⁺ (2, 8, 8), like argon.
Why the other options are wrong
- b Cr: Cr is not an inert gas; ions reach inert-gas configurations.
- c Kr: Kr has 36 electrons; K⁺ has only 18. The answer the book supports is Ar.
- d Sr: Sr is not an inert gas; K⁺ is like argon.
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