Which of the following statements is true?
2016
Which of the following statements is true?
- A.
Bases are sweet to taste
- B.
Vinegar is a natural source of lactic acid
- C.
Litmus is the most common indicator used in the laboratory
- D.
In an acidic medium, the turmeric paper turns reddish brown
Attempted by 210 students.
Show answer & explanation
Correct answer: C
Key point: Litmus paper is a natural acid-base indicator extracted from lichens.
In an acidic medium, blue litmus turns red.
In a basic (alkaline) medium, red litmus turns blue.
Because of these clear color changes, litmus is widely used in schools and chemistry labs to test whether a solution is acidic or basic.
Why the other statements are incorrect:
The claim that bases are sweet to taste is wrong. Bases typically taste bitter and feel soapy or slippery. Also, tasting chemicals to identify them is unsafe and should never be done in the lab.
The claim that vinegar is a natural source of lactic acid is incorrect. Vinegar contains acetic (ethanoic) acid, produced by acetic acid bacteria acting on ethanol. Lactic acid is found in fermented dairy products such as curd and yogurt.
The claim that turmeric paper turns reddish-brown in acidic medium is incorrect. Turmeric (curcumin) turns reddish-brown in alkaline (basic) conditions; in acidic media it remains yellow.
Conclusion: Litmus is the correct and most commonly used indicator among the given statements, because of its clear and reliable colour change between acidic and basic media.