Chlorine and bromine are in Group 7 of the periodic table. State one similarity and one difference between the electronic structures of a chlorine atom and a bromine atom.

A student mixes different aqueous halogens with aqueous halide solutions to observe displacement reactions.

Which of the following mixtures will undergo a displacement reaction?

• Bromine water and sodium chloride solution
• Iodine solution and sodium bromide solution
• Chlorine water and sodium iodide solution
• Iodine solution and sodium chloride solution

Which of the following correctly describes the trends in properties of the halogens as Group 7 is descended?

• Electronegativity increases and first ionisation energy increases.
• Electronegativity decreases and first ionisation energy decreases.
• Electronegativity increases and first ionisation energy decreases.
• Electronegativity decreases and first ionisation energy increases.