As part of the Science Exhibition, Class VII students prepared red rose extract and turmeric paper to identify the nature of common household substances. They also carried red litmus paper, blue litmus paper, and onion as an olfactory indicator.
A visitor brought an unknown liquid for testing. The students observed the following:
- Blue litmus paper turned red.
- Red litmus paper showed no change.
- Turmeric paper remained yellow.
- Red rose extract remained red.
- The onion retained its characteristic smell.
The students concluded that the unknown liquid was acidic.
Choose the correct answer:
Which observation gives the strongest evidence that the unknown liquid is acidic?