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 $+66^{\circ},+140^{\circ},-52^{\circ}$ and $+92^{\circ}$, respectively)

• A. 'invert sugar' is prepared by acid catalyzed hydrolysis of maltose
• B. 'invert sugar' is an equimolar mixture of $D -(+)$-glucose and $D -(-)$ fructose
• C. specific rotation of 'invert sugar' is $-20^{\circ}$
• D. on reaction with $Br _{2}$ water, 'invert sugar' forms saccharic acid as one of the products

Answer 1

Answer: (B), (C)

(A) Wrong invert sugar is formed by sucrose not by maltose
(B) Equimolar mixture of $D (+)$ glucose and $D (-)$-fructose
(C) specific rotation of invert sugar is $-20^{\circ}$

Invert sugar is hydrolysed sucrose, initially sucrose is dextrorotatory but finally solution is laevorotatory.
(ii) Specific rotation is average of both optical rotation of glucose and fructose
Specific rotation $=\frac{\theta_{\text {Glucase }}+\theta_{\text {Fnstose }}}{2}$
$=\frac{+52-92}{2}=-20^{\circ}$
(D) Glucose $\ce{->[Br_2/H_2O]}$ Gluconic acid (NOT saccharic acid) Wrong