Group 7 Practice Questions

Which of these describes bromine at room temperature?

Put a cross ( ☒ ) in the box next to your answer.

☐ A red-brown liquid

☐ B yellow liquid

☐ C dark-grey solid

☐ D pale green gas

State the colour and the physical state of iodine at room temperature.

Name the compound formed when hydrogen reacts with iodine.

Astatine is below iodine in Group 7.

Predict what would be seen if hydrogen astatide gas were dissolved in water and a few drops of universal indicator were then added.

Explain your prediction.

Describe what the student would see if the gas is chlorine.

A second student tests a different gas. The damp blue litmus paper turns red but stays red.

The second student says this gas must be chlorine.

Give a reason why this conclusion is incorrect.

Describe the trend in the melting points and boiling points of the halogens going down Group 7.

Use the data in the table to explain why bromine is a liquid at a room temperature of $20\ ^\circ\mathrm{C}$.

Fluorine is above chlorine in Group 7.

Predict the physical state of fluorine at $20\ ^\circ\mathrm{C}$.

Name the compound formed when hot iron wool reacts with bromine vapour.

Aluminium reacts with iodine to form aluminium iodide.

Write the balanced equation for this reaction.

Bromine water is added to potassium iodide solution and the mixture is shaken.

Describe what the student would see.

The student then adds iodine solution to potassium bromide solution. No reaction takes place.

Explain why.

Explain, in terms of electrons, why the iodide ions are oxidised in this reaction.

Write the half equation for the reduction of chlorine in this reaction.

Give one reason why this investigation must be carried out in a fume cupboard.

Describe how the student should use these solutions to find the order of reactivity of chlorine, bromine and iodine.

Deduce the order of reactivity of these three halogens, starting with the most reactive.

Astatine is below iodine in Group 7.

Predict what would be seen when chlorine solution is added to potassium astatide solution, and what would be seen when iodine solution is added to potassium astatide solution.

Explain your predictions.

A student sets up two test tubes.

• Tube A: chlorine solution is added to colourless potassium iodide solution.
• Tube B: brown iodine solution is added to colourless potassium chloride solution.

Explain what the student would observe in each tube.

Your answer should refer to the relative reactivity of the halogens and to the transfer of electrons.

Fluorine is more reactive than bromine.

Explain this difference in reactivity in terms of the electronic configurations of the atoms.