Glucose, Fructose and Mannose give the same osazone because these sugars have the same configuration of carbons 3, 4, 5 and 6. osazone formation only affects carbons 1 and 2.

glucose and fructose form same osazone crystals because carbon no 1 to carbon no 6 are identical both in glucose and in fructose

Reagents of Osazone test are 1. Phenylhydrazine mixture consisting of phenyl-hydrazine and anhydrous sodium citrate 2. Orignal solution containing a carbohydrate

D-erythrose and D-threose both yield the same osazone. Likewise, L-erythrose and L-threose yield the same osazone.

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