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JAMB Chemistry 2017 Objective — Question 12

Question 12 of 40 from the Joint Admissions and Matriculation Board (JAMB) Chemistry 2017 Objective paper, with the correct answer and a full explanation.

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When a few drops of concentrated trioxonitrate(V) acid are added to an unknown sample and warmed, an intense yellow colouration is observed. The likely functional group present in the sample is shown in the diagram (structures for options A-D).

  • A. A. the carboxylic acid group (-C-C=O with R and OH)Correct
  • B. B. -CHO (aldehyde group)
  • C. C. C=O (ketone group)
  • D. D. an amide group (-C(=O)NH2)

Explanation

This is the xanthoproteic test for protein. The functional groups present in protein are the amino group (-NH2) and the carboxyl group (-COOH), matching structure A.

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