Question

For ‘invert sugar’, the correct statement(s) is/are:
(Given: Specific rotations of (+)-sucrose, (+)-maltose, L-(–)-glucose and L-(+)-fructose in aqueous solution
are $+{66}^o,+{140}^o,–{52}^o$ and $+{92}^o$ respectively)

• A. Specific rotation of invert sugar is $-{20}^o$
• B. Specific rotation of invert sugar is $+{20}^o$
• C. ‘Invert sugar’ is an equimolar mixture of D-(+)-glucose and D-(–)-fructose
• D. ‘Invert sugar’ is prepared by acid catalyzed hydrolysis of maltose

Answer 1

Answer: (A), (C)

The correct options are
A Specific rotation of invert sugar is $-{20}^o$
C ‘Invert sugar’ is an equimolar mixture of D-(+)-glucose and D-(–)-fructose

$C_{12}{H}_{22}{O}_{11}\underset{H_{2}O}{\overset{H^{+}}{\to }}\underset{D-(+)-glucose}{C_6{H}_{12}{O}_6}+\underset{D-(-)-fructose}{C_6{H}_{12}{O}_6}$

Specific rotation of D-(+)-glucose is $+{52}^o$ and that of D-(-)-fructose is $-{92}^o$.

$\therefore {\alpha }_{\text{invert sugar}}=\frac{+{52}^o+(-{92}^o)}{2}=-{20}^o$