Question

Assertion Sucrose is a non-reducing sugar. Reason It has glycosidic linkage.
A. Both Assertion and Reason are correct, and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct, but Reason is not the correct explanation for Assertion
C. Assertion is correct, but Reason is incorrect
D. Both Assertion and Reason are incorrect

Answer 1

Sugars that do not have free ketone or aldehyde group are called non-reducing sugars. These sugars have acetal instead of hemiacetal. Acetal consists of two ${{O - R}}$ group, one ${{ - R}}$ and ${{ - H}}$ group respectively, all of these groups are attached with the same carbon.

Complete step by step answer:
Some common examples of non-reducing sugar are sucrose, trehalose, raffinose, stachyose, verbascose
The most known non-reducing sugar is sucrose. The formation of hemiacetal is not favoured by the chemical structure of sucrose. The two monosaccharide units of sucrose are held together by a glycosidic linkage between ${{C_1}}$ of ${{\alpha - }}$ glucose and ${{C_2}}$ of ${{\beta - }}$ fructose so sucrose is a non-reducing sugar.
Reducing sugars is a carbohydrate whose structure consists of an aldehyde, or a hemiacetal in equilibrium with an aldehyde. Carbohydrates containing free aldehyde or ketone functional groups are thus reducing sugars.
Non-Reducing Sugar Test: If the given sugar is reducing or non-reducing in nature is identified by Benedict’s test. Benedict’s solution is added to the given sugar and the color change is noted, if there is no change in the colour, then it is a non-reducing sugar. If there is a change in the colour of the sugar, then it is a reducing sugar.

Hence the answer is option A. Both Assertion and Reason are correct, and Reason is the correct explanation for Assertion.

Additional Information:
The most common hexoses are $\left( {{D}} \right)$-glucose, $\left( {{D}} \right)$-fructose, $\left( {{D}} \right)$-galactose, and $\left( {{D}} \right)$-mannose. These all are aldohexoses, except $\left( {{D}} \right)$-fructose, it is a ketohexose.

Note: Monosaccharides are the building blocks of carbohydrates. They can be said as polyhydroxy aldehydes or ketones containing five, six, seven, or eight membered carbon atoms. They are classified as pentoses, hexoses, heptoses, and octoses, respectively. They can more specifically be expressed by the kind of carbonyl compound present, such as aldohexose or ketohexose.
For example, a five membered carbon sugar with aldehyde as carbonyl group is an aldopentose and a six membered carbon sugar with a ketone as carbonyl group is a ketohexose.