13028 [Turn over 12 The halogens are Group VII in the Periodic Table. (a) Compare the colour and relative solubility of iodine in water and hexane. [3] (b) The boiling points of the hydrogen halides are shown in the table below. Hydrogen halide HF HCl HBr HI Boiling point /°C 20 −85 −67 −35 Explain the change in boiling points of the hydrogen halides. [4] 13028 (c) Bromine is an important reagent in producing chemicals such as NaBrO and NaBrO3. (i) Give the systematic names of NaBrO and NaBrO3. NaBrO NaBrO3 [2] (ii) NaBrO and NaBrO3 can be prepared by the reaction of bromine with sodium hydroxide solution. State the conditions and write the equations for the formation of NaBrO and NaBrO3. NaBrO Conditions: Equation: NaBrO3 Conditions: Equation: [6] (iii) Describe the test to show the presence of bromide ions in solution. [2] 13028 [Turn over (d) Both chlorine and ozone can be used in the treatment of drinking water. (i) Give one advantage and one disadvantage of chlorine and ozone in treating drinking water. chlorine Advantage: Disadvantage: ozone Advantage: Disadvantage: [4] (ii) Describe the test to identify chlorine gas. [2]