Which of the following ions interfere with the brown ring test for nitrate (that is, give a brown ring or a coloured vapour/layer that masks it) if not removed beforehand? One or more options may be correct.

Nitrite gives the brown nitrosyl complex itself. Bromide and iodide are oxidised by concentrated $\mathrm{H}{}_2\mathrm{SO}{}_4$ to brown $\mathrm{Br}{}_2$ and violet/brown $\mathrm{I}{}_2$, which mask the ring. Chloride gives only colourless HCl and does not interfere. Correct: first three.