Question

Which of the followings is invert sugar?

• A. Sucrose
• B. Cellulose
• C. Glucose
• D. Fructose

Answer 1

Answer: (A)

Sucrose

Answer 2

Sucrose is dextrorotatory but on hydrolysis it gives an equimolar mixture of dextrorotatory $[D-(+)]-$ glucose and laevorotatory $[D-(-)-]$ fructose. As the laevorotation of fructose $(-92^{\circ} 4^{\circ})$ is much more than dextrorotation of glucose $(+52.5^{\circ})$, therefore, the resulting mixture becomes laevorotatory. Therefore, the hydrolysis of sucrose is accompanied by a change in sign of optical rotation from dextrorotatory to laevorotatory. Therefore, sucrose is called invert sugar.