A few drops of universal indicator turn a colourless solution red. What does this show about the solution?
Answer and explanation
Correct answer: D. It is strongly acidic, with a pH of about to
- Step 1: Universal indicator changes through a colour range: red, orange, yellow, green, blue, purple.
- Step 2: Red is at the acidic end of the scale, at a pH of about to .
Answer
It is strongly acidic, with a pH of about to .
Why not the others: It is strongly alkaline, with a pH of about to : strong alkalis turn universal indicator purple. It is neutral, with a pH of : neutral solutions turn universal indicator green. It is weakly alkaline, with a pH of about : weak alkalis turn universal indicator blue.
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