निम्नलिखित सल्फाइडों पर विचार कीजिए: HgS, PbS, CuS, Sb2S3, As2S3, और CdS। इनमें से कितने सल्फाइड 50% HNO3 में विलेय हैं?

In a test tube containing a salt, a few drops of dilute H2SO4 were added, which evolved colorless vapors with a characteristic vinegar smell. The vapors turned moist blue litmus paper red. Identify the anion present in the salt:

The functional group that can be identified through phthalein dye test is: