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Question:

The peptide that gives positive ceric ammonium nitrate and carbylamine tests is:

Lys-Asp

Asp-Gln

Gln-Asp

Ser-Lys

Solution:

Correct option is B. Ser-Lys
Serine →HO−C=O−C|NH2H−CH2−OH
Lysine →H2N−CH2−CH2−CH2−CH2−CH|NH2−O=O−OH
Lysine has −NH2 group hence gives positive carbyl amine test and serine has −OH group hence gives positive cerric ammonium nitrate test.