Which of the following reagents is used to identify one primary...

Glucose contains one primary alcoholic group at the C-6 position.

When glucose is treated with dilute $\text{HNO}_3$, both the terminal aldehyde group and the primary alcoholic group are oxidized to carboxylic acid groups, resulting in the formation of saccharic acid (glucaric acid).

This specific oxidation reaction confirms the presence of a primary alcoholic group in glucose.

$\text{Br}_2$ water is a mild oxidizing agent that oxidizes only the aldehyde group to form gluconic acid, confirming the presence of an aldehyde group.

Acetic anhydride forms glucose pentaacetate, confirming the presence of five hydroxyl groups.

$\text{NH}_2\text{OH}$ forms an oxime, confirming the presence of a carbonyl group.

Answer: dilute $\text{HNO}_3$