Question

Which of the following statements are true?
(1) Maltose forms an osazone
(2) Lactose undergoes mutarotation.
(3) Galactose is a $C_4$-epimer of glucose
(4) In starch, the glucose units are linked by " $\beta$-linkages

• A. 1, 2 and 3 are correct
• B. 1 and 2 are correct
• C. 2 and 4 are correct
• D. 1 and 3 are correct

Answer 1

Answer: (A)

Maltose, $\left(C_{12}{H}_{22}{O}_{11}\right)$, a disaccharide, reacts with phenyl hydrazine to give an osazone $C_{12}{H}_{20}{O}_9{\left(=N\cdot NH{C}_6{H}_5\right)}_2$.
All monosaccharide and reducing disaccharide undergo mutarotation.
The structure of glucose and galactose are as

Thus, galactose is $C-4$ epimer of glucose.
In starch, the glucose units are linked by $\alpha$-linkages.