Chlorine, bromine and iodine are Group 7 elements. A student investigated the reactivity of these elements.
The student added:
- aqueous chlorine to potassium bromine and potassium iodide solutions
- aqueous bromine to potassium chloride and potassium iodide solutions
- aqueous iodine to potassium chloride and potassium bromide solutions.
The student's results are shown below.

Solution | Potassium chloride | Potassium bromide | Potassium iodide

Chlorine | None | Solution turned orange-brown | Solution turned brown
Bromine | No reaction | None | Solution turned brown
Iodine | No reaction | No reaction | None

Use these results to state and explain the trend in reactivity of these Group 7 elements. (2)

b. accuracy of the data matters alot more than its number of digits, organization or amount of detail. quantitative observation is more accepted than the qualitative observation.

intermolecular forces are the forces between molecules or particles.

there are two kinds of van der waals forces: weak london dispersion forces and stronger dipole-dipole forces.

in molecule of water there are dipole-dipole forces between negatively charged oxygen from one molecule of water and positively charger hydrogen of another molecule of water.

hydrogen bond is an electrostatic attraction between two polar groups that occurs when a hydrogen atom (h), covalently bound to a highly electronegative atom such as flourine (f), oxygen (o) and nitrogen (n) atoms.