The teacher asked the students to correctly record the results of the experiment done to detect the presence of metanil yellow in the adulterated arhar dal sample that was provided to them. Which one of the following observations is correct?
of metanil yellow
D) 5 g dal + 5 ml water + 2 drops of HCl metanil yellow present
options-
A
B
C
D
Answers
Answer:
MATERIALS REQUIRED
Samples of food material (boiled rice or boiled potato), test tubes, test tube holder, iodine solution, distilled water.
THEORY
Starch is a complex carbohydrate which consists of many glucose molecules. It gives blue-black colour with iodine solution.
PROCEDURE, OBSERVATION AND INFERENCE
CBSE Class 9 Science Practical Skills – Food Sample Test for Starch and Adulteration 1
RESULT
The given food sample (rice/potato) contains starch.
PRECAUTIONS
Use reagents/chemicals judiciously.
Always use a clean test tube.
(2) To test the presence of the adulterant metanil yellow in dal.
MATERIALS REQUIRED
Dal, cone. HCl, distilled water, test tubes, test-tube holder, test-tube stand.
THEORY
Metanil yellow is a synthetic dye which is not permitted to use as food colour. However, it is extensively used to give yellow colour to dal and turmeric. It is toxic in nature and it has adverse effects on liver, intestine and brain. Presence of metanil yellow can be tested in dal by adding few drops of hydrochloric acid to a test sample. If the test solution turns pink in colour, it indicates presence of metanil yellow.
PROCEDURE, OBSERVATION AND INFERENCE
CBSE Class 9 Science Practical Skills – Food Sample Test for Starch and Adulteration 2
RESULT
Metanil yellow is present as adulterant in dal.
PRECAUTIONS
Use chemicals judiciously.