Test the presence of adulterant metanil yellow in dal
To test the presence of metanil yellow in dal, take the following steps:
- Take approximately 5 gms of dal in a test tube and add 5 ml of water.
- Shake the test tube well.
- Add few drops of concentrated hydrochloric acid to the test tube. (This activity should be done in the presence of your school teacher).
- The appearance of a pink colour in the solution confirms the presence of metanil yellow in dal
(MCQs asked in CBSE examination)
Q1: Metanil yellow changes the colour of solution of dal to
(d) dark red
Q2: Adulterated Arhar dal seems to be plain yellow because of the adulterant
(c) metanil yellow
(d) basic yellow
Q3: To check the adulteration properly,dal is cooked with metanil yellow and ____is added.
(a) conc. HCl
(b) Conc. H2SO4
(c) Iodine sol.
Q4: Metanil yellow is basically:
(a) A base used to cook some foods.
(b) An acid used to neutralize base
(c) A chemical used in detergents.
(d) An inorganic dye used in leather,paper and textile industry.
Q5: Four students A,B,C and D carried out a test for the adulteration of metanil yellow in arhar dal and recorded their observations as given below. The procedure followed correctly is by the student____. The procedures were
|A||5 g dal+ 5g metanil||Dal turns yellow||Metanil Yellow present|
|B||5 g dal+ 5 ml water+|
2drops of HCl
|solution turns pink/magenta||Metanil yellow present|
|C||5 g dal+ 5 ml water+|
pinch of Metanil yellow
|Water turns yellow||Metanil yellow present|
|D||5 g dal+ 5 ml water+|
2 drops HCl
|Water turns yellow|
and then pink
|Metanil yellow absent|
Q6: Deepak washed a few grains of tur dal in water. The water became yellow.He then added a few drops of HCl to the same test tube, the water turned pink in colour. From the above test Deepak concluded that tur dal contains:
(d) metanil yellow
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1) (b) pink
2) (c) metanil yellow
3) (a) conc. HCl
4) (d) An inorganic dye used in leather,paper and textile industry.
5) (b) B
6) (d) metanil yellow