The reaction of glucose with nitric acid will yield

The correct answer is Option (2) → saccharic acid.

The open-chain structure of glucose has an aldehyde group (–CHO) at C1, four secondary –OH groups, and one primary alcoholic group (–CH₂OH) at C6. Each reaction of glucose reveals one feature of this structure:

• Bromine water (mild oxidant) oxidises only –CHO to –COOH, giving gluconic acid: this shows the aldehyde group.

• Nitric acid (strong oxidant) oxidises both ends: –CHO and the primary –\( \ce{CH2OH} \) both become –COOH, giving the dicarboxylic acid saccharic acid (glucaric acid).

    \( \displaystyle \underset{\text{glucose}}{\ce{OHC-(CHOH)4-CH2OH}} + \ce{3[O]} \xrightarrow{\ce{HNO3}} \underset{\text{saccharic acid}}{\ce{HOOC-(CHOH)4-COOH}} + \ce{H2O} \)

Only a primary alcohol group can be oxidised to –COOH without losing a carbon, so the formation of saccharic acid shows that glucose contains a primary alcoholic group. So the reaction of glucose with nitric acid yields saccharic acid.

Why the other options are incorrect

• Option (1) gluconic acid. — Incorrect. It is formed with bromine water; it shows the aldehyde group, since only C1 is oxidised.

      \( \displaystyle \ce{OHC-(CHOH)4-CH2OH} \xrightarrow{\ce{Br2}\text{ water}} \underset{\text{gluconic acid}}{\ce{HOOC-(CHOH)4-CH2OH}} \)

• Option (3) gluconic acid + saccharic acid. — Incorrect. Nitric acid does not stop at gluconic acid; the product is saccharic acid alone.

• Option (4) nitroglucose. — Incorrect. Nitric acid acts here as an oxidising agent, not as a nitrating agent, so no nitro compound forms.

NCERT (2026-27 edition):
Glucose – …

Note: The same/similar question has been asked in different years by NTA as per the details given below: