Blue cobalt chloride paper turning pink indicates the presence of what substance?

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Multiple Choice

Blue cobalt chloride paper turning pink indicates the presence of what substance?

Explanation:
Cobalt chloride paper acts as a moisture indicator. When it’s dry, it appears blue. If it absorbs water, the cobalt(II) ions form a hydrated complex that is pink. So, a pink color shows water is present (either as liquid water or moisture in the air). Alcohol, oil, or salt wouldn’t cause this hydration-induced pink change in the same way, so pink specifically signals water. If you dry the paper, it usually returns to blue.

Cobalt chloride paper acts as a moisture indicator. When it’s dry, it appears blue. If it absorbs water, the cobalt(II) ions form a hydrated complex that is pink. So, a pink color shows water is present (either as liquid water or moisture in the air). Alcohol, oil, or salt wouldn’t cause this hydration-induced pink change in the same way, so pink specifically signals water. If you dry the paper, it usually returns to blue.

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