Which element from following rapidly loses its luster in air and tarnishes?

Which element from following rapidly loses its luster in air and tarnishes?
  1. Ba
  2. Be
  3. K
  4. Mg

Solution

Elements of group 1 rapidly lose their luster in air due to formation of a layer of exide, peroxide or superoxide by reaction with oxygen in air.

Asked in: MHT CET 2023 (14 May Shift 2)

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