On addition of conc. H2SO4 to a chloride salt, colourless fumes are evolved but in case of an iodide salt, violet fumes come out. This is because (i) H2SO4 reduces HI to I2 (ii) HI is of violet colour (iii) HI gets oxidised to I2 (iv) HI changes to HIO3
Option 3) When chloride salts are treated with sulfuric acid, HCl gas is formed, which produces a colourless gas. Violet fumes are produced during the reaction as a result of the formation of iodine gas.
