Question

what are the tests for nitrogen dioxide?​

Answer 1

Two major indications :

the colour (reddish brown)

the smell ("biting" -  it is very toxic)

Hope this helps ;)

Answer 2

Answer:

Chemical test for nitrogen(IV) oxide nitrogen dioxide NO2

The other common orange–brown gas is bromine. Its a strong oxidising agent. Dissolved in water it gives a solution of nitrite and nitrate ions. The other common brown gas is bromine and the solution of nitrogen dioxide shouldn't give a cream ppt.