Question

Which of the following statement(s) is (are) true?
This question has multiple correct options.
(A) The two six membered cyclic hemiacetal forms of D− (+) − glucose are called anomers
(B) Hydrolysis of sucrose gives dextrorotatory glucose and laevorotatory fructose
(C) Monosaccharides cannot be hydrolyzed to give polyhydroxy aldehydes and ketones
(D) Oxidation of glucose with bromine water gives glutamic acid

Answer 1

Hint: Both fructose and glucose are monosaccharides and they have cycle structures and open chains assigned to them. A part of the properties of these molecules can be explained by cyclic structures and some properties by the open chain structure.

Complete solution:
- The carbohydrates play an important role in the sustainment of life through its various functions such as the source of energy in animals, structural material to plants metabolic materials in plants and as components of biomolecules. As we know, fructose and glucose are monosaccharides with a molecular formula of ${{C}_{6}}{{H}_{12}}{{O}_{6}}$.
-The first statement is about the two six membered cyclic hemiacetal forms of D− (+) − glucose and they can be represented as follows:

These two six membered cyclic hemiacetal forms of D− (+) − glucose are also called as anomers and here the ${{C}_{1}}$ carbon is the anomeric carbon. Hence, the statement (A) is correct.
- The hydrolysis reaction of sucrose can be represented as follows:
\[{{C}_{12}}{{H}_{22}}{{O}_{11}}\xrightarrow{{{H}_{2}}O}{{C}_{6}}{{H}_{12}}{{O}_{6}}+{{C}_{6}}{{H}_{12}}{{O}_{6}}\]
 Thus when sucrose is hydrolyzed dextrorotatory glucose and laevorotatory fructose are formed as the products. So, the statement (B) is also correct.
- The hydrolysis reaction of monosaccharides can be represented as follows:
\[{{C}_{6}}{{H}_{12}}{{O}_{6}}+{{H}_{2}}O\to No\text{ }reaction\text{ }\]
Hence, the monosaccharides cannot be hydrolyzed to give polyhydroxy aldehydes and ketones. Thus the statement (C) is also correct.
- The product formed by the oxidation of glucose with bromine water is gluconic acid not glutamic acid and the reaction can be represented as follows:
\[{{C}_{6}}{{H}_{12}}{{O}_{6}}\xrightarrow[{{H}_{2}}O]{B{{r}_{2}}}Gluconic\text{ }acid\]
Thus, the statement (D) is incorrect.

Therefore, the answers are options (A), (B) and (C).

Note: Keep in mind that, another monosaccharide galactose also has the same chemical formula of glucose and fructose ${{C}_{6}}{{H}_{12}}{{O}_{6}}$ and hence the molecule galactose and glucose are stereoisomers. Also, the carbohydrates are generally classified into three categories such as monosaccharides, oligosaccharides and polysaccharides.