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KCET · Chemistry · Chemistry in Everyday Life

The statement that is NOT correct is

  1. A Carbohydrates are optically active,
  2. B Lactose has glycosidic linkage between \( C_{4} \) of glucose and \( C_{1} \) of galactose unit.
  3. C Aldose or ketose sugars in alkaline medium do not isomerism.
  4. D Pentaacetate of glucose does not react with hydroxylamine.
Verified Solution

Answer & Solution

Correct Answer

(C) Aldose or ketose sugars in alkaline medium do not isomerism.

Step-by-step Solution

Detailed explanation

Aldose or ketose sugars in alkaline medium isomerize. For example; on heating with conc. solution of \( \mathrm{NaOH} \) glucose
(aldose) first turns yellow and then brown and finally resinifies with dilute solution of \( \mathrm{NaOH} \) glucose (aldose) undergoes a
reversible isomerization and is converted into a mixture of D-glucose, D-maltose and D-fructose. This reaction is known
as lobry de Bruyn-van Ekenstein rearrangement.