An investigator demonstrated the reactivity trend of Group 7 elements by passing different halogen vapours over heated iron wool. Their observations are recorded in Table 1.
Table 1
| Halogen | Observation of reaction with heated iron wool |
|---|---|
| Chlorine | Reacts vigorously with a bright orange glow, producing a brown solid |
| Iodine | Reacts very slowly with a faint, dull glow only when heated strongly |
| Bromine | Reacts steadily with a moderate orange glow, producing a red-brown solid |
Give the name of the halogen in Table 1 that is the least reactive with iron.
106 exam-style questions on Edexcel GCSE Chemistry 7.2 Group 7, covering 7.2.1 Physical properties of the halogens, 7.2.2 Reactions of the halogens, 7.2.3 Relative reactivity and displacement reactions of the halogens, and 7.2.4 Halogen displacement as a redox reaction. Each one has a worked solution and a mark scheme showing where the marks go.