What functional group gives a positive test in the xanthoproteic test?

An aromatic group is a functional group which gives a positive test in a xanthoproteic test.

Xanthoproteic is a test for protein detention. The concentrated nitric acid reacts with proteins if they are present to form yellow colour. By adding alkali it turns orange-yellow through xanthoproteic reaction. Due to a phenyl group, the hydroxyl group can make the test positive in xanthoproteic.

An aromatic group consists of six hydrocarbons with an alternating single and double bond between carbon atoms which form rings.