Question

Four test tubes of tuhar dal were taken with some water in each and labelled as A, B, C and D. A few drops of the following were added to these test tubes.
Which of the test tube would be able to confirm the presence of metanil yellow adulterant ?

• A. Test tube A to which NaOH was added.
• B. Test tube B to which HCl was added.
• C. Test tube C to which alcohol was added.
• D. Test tube D to which water was added.

Answer 1

Answer: (B)

Test tube B to which HCl was added.

• The dal is adulterated with a yellow coloured dye called metanil yellow.
• The adulterant can be detected with the help of hydrochloric acid.
• When a few drops of hydrochloric acid are added to the dal with metanil yellow, the colour of the solution turns pink.
• This change in colour indicates that the dal is adulterated with metanil yellow.
  

Thus, the correct answer is option B.