Question

Which of the following ions can turn red litmus paper blue?

• A. H\textsuperscript{+}
• B. OH\textsuperscript{--}
• C. O\textsuperscript{2--}
• D. None of these

Hint:

Acids release H\textsuperscript{+} (turn blue litmus red), bases release OH\textsuperscript{--} (turn red litmus blue).

Answer 1

The Correct Option is B

Step 1: Recall.
Red litmus turns blue in alkaline/basic medium.
Step 2: Explanation.
OH\textsuperscript{--} ions are responsible for basic nature. Thus, they turn red litmus paper blue.
Step 3: Conclusion.
So, the correct answer is OH\textsuperscript{--}.