On addition of conc. H2SO4 to a chloride salt, colourless fumes are evolved but in case of iodide salt, violet fumes come out. This is because


On addition of concentrated H2SO4 to iodide salt violet fumes comes out because HI formed during the reaction react with oxygen present in the atmosphere to form I2 which is violet in colour.

2NaCl + H2SO4 Na2SO4 + 2HCl


HCl produced during the reaction is colourless and pungent smelling gas.


2NaI + H2SO4 Na2SO4 + 2HI 2H2O + SO2 +I2


Thus the halogen acid(HI) obtained in this reaction is oxidized to form I2.


Hence the correct option is (iii).

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