Question

name the reagent used in the reaction ,"oxidation of primary alcohol to carboxylic acid."

Answer 1

The reaction starts with the formation of an organic nitric acid ester (as these compounds are dangerously unstable, as Uncle Al already pointed out, I would not recommend to use nitric acid for this oxidation). The negatively charged nitrate oxygen abstracts an alpha proton from the alkyl group, and HNO2 is eliminated, yielding the aldehyde. Nucleophilic attack of nitrate on the carbonyl group and subsequent elimination of another equivalent HNO2 finally yields the carboxylate.