In the test of halogen, why the nitric acid is added before the silver nitrate sodium fusion extract?

In the test of halogen, why the nitric acid is added before the silver

1.	In the test of halogen, why the nitric acid is added before the silver nitrate sodium fusion extract?
Answer» SOLUTION :In sodium fusion extract, the sodium HYDROXIDE is in by the reaction between sodium and water, in which directly `AgNO_(3)` added and form precipitate AgOH. By ADDING of `HNO_(3)`, neutrallisation of NAOH is occurs and the solution become acidic and there is no interference in test of halogen.