A student is given an aqueous solution containing an unknown halide ion, $Y^{-}$. To identify the ion, they perform two separate chemical tests:

• Test 1: They add dilute nitric acid followed by silver nitrate solution. A precipitate forms. They then add dilute aqueous ammonia, followed by concentrated aqueous ammonia.
• Test 2: They add concentrated sulfuric acid to a solid sample of the sodium salt, $NaY$.

The student records the following observations:

• In Test 1, the precipitate is insoluble in dilute ammonia but soluble in concentrated ammonia.
• In Test 2, a mixture of gases is produced, including orange-brown fumes and a choking gas that turns acidified potassium dichromate(VI) paper from orange to green.

Which row correctly identifies the halide ion $Y^{-}$, the colour of the silver halide precipitate, and the chemical formula of the choking gas?