A test tube containing a nitrate and another containing a bromide and ${\mathrm{MnO}}_2$ are treated with concentrated  ${\mathrm{H}}_2{\mathrm{SO}}_4$. The reddish brown fumes evolved are passed through water. The water will be coloured by:

${\mathrm{Br}}_2$ is highly soluble in water (red coloured). Conc.${\mathrm{H}}_2{\mathrm{SO}}_4$ is applied to test tubes containing nitrate and bromide and ${\mathrm{MnO}}_2$, respectively. The brown emissions move across water. The bromide will impart colour to the water.

$2\mathrm{KBr}+{\mathrm{H}}_2{\mathrm{SO}}_4\to {\mathrm{K}}_2{\mathrm{SO}}_4+2\mathrm{HBr}\uparrow$

$2\mathrm{HBr}+{\mathrm{H}}_2{\mathrm{SO}}_4\to 2{\mathrm{H}}_2\mathrm{O}+{\mathrm{SO}}_2\uparrow {\mathrm{Br}}_2\uparrow \text{ (reddish brown) }$