Year 9 Chemical Reactions Properties, Equations, And Energy Changes Practice Test

Litmus test: how can you distinguish acids and bases using litmus paper? What colors indicate each?

Acids turn blue litmus red; bases turn red litmus blue. Acids turn red litmus blue; bases turn blue litmus red. Acids and bases both turn blue litmus red. Bases both turn red litmus blue.

Correct Answer:

Acids turn blue litmus red; bases turn red litmus blue.

Explanation:

Litmus paper is a simple pH indicator that changes color depending on how acidic or basic a solution is. In acidic solutions, blue litmus turns red. In basic (alkaline) solutions, red litmus turns blue. Neutral solutions don’t cause dramatic color changes for either paper, so blue stays blue and red stays red. So, when you’re distinguishing acids and bases, acids make blue litmus red, and bases make red litmus blue. Using both papers helps you confirm: a blue paper turning red indicates acidity, while a red paper turning blue indicates basicity.

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