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Hansa, a class XII student, was discussing diazonium salts. She emphasized that although azo dyes are excellent for dyeing fabric but the food coloured with azo dyes is harmful particularly for young children and asthma patients. Therefore, she stressed that only natural dyes should be used for colouring food. After reading the above passage, answer the following questions :
(i) What are azo dyes? Give one example.
(ii) Name an azo dye which has been used as a food colour in the past but has now been banned?
(iii) Name a few natural food dyes. (iv) What values are expressed by Hansa.
Answers
Answer:
Azo-dye Test is the combination of Di-azotisation reaction and the coupling reaction to form the coloured dye.
This test is used to identify the presence of primary aromatic amine.
He should not write the labels with ink because the ink label itself will start moving along with the colours of the dyes and cause difficulty in int
erpretation of the results.
b)i)yellow food colouring contained the banned food dye.
ii)The brown food colouring contained most dyes
c) The red food colouring did not dissolve in water
d) The method used is Chromatography.
Reaction Involved (In second step, phenol is the coupling reagent which couples with Di-azonium salt)-
Calcium carbonate is a common, naturally occurring carbonate it is a major component of marble, limestone and the skeleton of coral.
2. Magnesium carbonate is also a naturally occurring carbonate it is ordinarily obtained by mining the mineral magnesite.
Hope it helps
