Question

Invert sugar is:
(A) a type of cane sugar
(B) optically inactive form of sugar
(C) mixture of glucose and galactose
(D) mixture of glucose and fructose in equimolar quantities

Answer 1

Hint: Recollect the concept of carbohydrates. Think which sugar is called invert sugar and what the process inversion is. Revise the concept of hydrolysis of polysaccharides to give simpler monosaccharides and then try to think about each option to get the right answer.

Complete step by step solution:
- Carbohydrates are polyhydroxy derivatives of aldehydes or ketones.
- Carbohydrates are classified into monosaccharides, oligosaccharides and polysaccharides.
- Monosaccharides are the carbohydrates which are present in the simplest form and cannot be hydrolyzed further. For example, glucose, fructose, ribose, etc.
- Oligosaccharides are the carbohydrates which are made up of two to seven monosaccharides with the help of glycosidic linkages among them. Oligosaccharides can be hydrolyzed to give simpler monosaccharides. For example, sucrose, maltose, etc.
- Polysaccharides are polymers of monosaccharides or oligosaccharides. For example, starch, cellulose, etc.
- An invert sugar is carbohydrate which on inversion gets converted from one optical rotatory form to another, that is, dextro (+) to laevo (-) or laevo (-) to dextro (+) form.
- Sucrose is a sugar which is made up of equimolar quantities of glucose and fructose. Sucrose on hydrolysis gives glucose and fructose in the same number of moles.
- Sucrose during the process of hydrolysis brings about a change in optical rotation and that's why the products are known as invert sugar.
- Therefore, an invert sugar is a mixture of glucose and fructose in equimolar quantities.

- Therefore, the answer is option (D).

Note: Remember sucrose is known as cane sugar and it is the table sugar which we use in food. Glucose is also known as grape sugar. An equimolar mixture of glucose and fructose is known as invert sugar. Lactose is a sugar made up of glucose and galactose and is known as milk sugar.