Read the passage carefully and answer the questions.

Carbohydrates such as cane sugar, glucose, starch etc. belong to a class of naturally occurring organic compounds. Structurally these are polyhydroxy aldehydes or ketones or the compounds which produce such units on hydrolysis. Carbohydrates which are sweet in taste are called sugars. Theses sugars can be reducing or non-reducing. Monosaccharides cannot be hydrolyzed to simpler units whereas Oligosaccharides yield two to ten monosaccharide units on hydrolysis. Polysaccharides yield large number of monosaccharide units on hydrolysis. This class of biomolecules is essential for living systems as they serve as storage molecules in plants and animals. In addition, they provide raw materials for important industries like furniture, textiles, paper, lacquers and breweries. Two aldopentose form important constituents of nucleic acids. Carbohydrates are also called saccharides (Greek: sakcharon which means sugar). Sugar which is used in household and in milk also comes under this class of biomolecules.

Which of the following is incorrect for glucose?

It is named as D (-) glucose

The correct answer is Option (1) → It is named as D (-) glucose

• It is named as D (–) glucose — Incorrect
  Glucose is correctly written as D (+) glucose, not D (–).
  The “D” refers to its configuration (relative to glyceraldehyde), and naturally occurring glucose is dextrorotatory (+).

• A reducing sugar — Correct
  Glucose has a free aldehyde group in its open-chain form, so it acts as a reducing sugar.

• It is an aldose — Correct
  Glucose contains an aldehyde functional group, therefore it is classified as an aldose.

• Six-membered cyclic structure is called pyranose — Correct
  When glucose forms a six-membered ring, the structure is known as glucopyranose (pyranose form).

Conclusion:
The only incorrect statement about glucose is “It is named as D (–) glucose.”