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Group 7 (halogens) – chlorine, bromine and iodine

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Question 1

A student is given an aqueous solution containing an unknown halide ion, Y−Y^-Y−. To identify the ion, they perform two separate chemical tests:

  • Test 1: They add dilute nitric acid followed by silver nitrate solution. A precipitate forms. They then add dilute aqueous ammonia, followed by concentrated aqueous ammonia.
  • Test 2: They add concentrated sulfuric acid to a solid sample of the sodium salt, NaYNaYNaY.

The student records the following observations:

  • In Test 1, the precipitate is insoluble in dilute ammonia but soluble in concentrated ammonia.
  • In Test 2, a mixture of gases is produced, including orange-brown fumes and a choking gas that turns acidified potassium dichromate(VI) paper from orange to green.

Which row correctly identifies the halide ion Y−Y^-Y−, the colour of the silver halide precipitate, and the chemical formula of the choking gas?

Halide ion = Br−Br^-Br−; Colour of precipitate = Cream; Choking gas = SO2SO_2SO2​

Halide ion = I−I^-I−; Colour of precipitate = Yellow; Choking gas = H2SH_2SH2​S

Halide ion = Br−Br^-Br−; Colour of precipitate = Yellow; Choking gas = HBrHBrHBr

Halide ion = Cl−Cl^-Cl−; Colour of precipitate = White; Choking gas = HClHClHCl

Group 7 (halogens) – chlorine, bromine and iodine Questions

  1. IGCSE
  2. /Chemistry
  3. /Group 7 (halogens) – chlorine, bromine and iodine