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GK QUESTION#3179

Assertion (A): Potassium reacts violently with cold water, producing hydrogen gas and heat. Reason (R): Potassium is an alkali metal with low reactivity.

  1. AA is true, but R is falseCorrect answer
  2. BBoth A and R are true, and R is the correct explanation of A
  3. CBoth A and R are true, but R is not the correct explanation of A
  4. DA is false, but R is true
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Answer

A. A is true, but R is false

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Explanation

Potassium reacts vigorously with cold water: 2K + 2H₂O → 2KOH + H₂, releasing heat. Its high reactivity contradicts the reason’s claim of low reactivity, so the assertion is true and the reason false.

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