Free Group VII questions for IGCSE Chemistry (0620), part of The Periodic Table. Each question has the answer and the marking points an examiner would look for.
Generate a full Group VII worksheet →All The Periodic Table questionsAqueous iodine is added to aqueous potassium bromide.
Does a reaction take place, and what is the colour of the final mixture?
| reaction? | colour of mixture | |
|---|---|---|
| A | no | brown |
| B | yes | brown |
| C | yes | colourless |
| D | no | orange |
Answer: A
Which term is described by this statement?
“The Group VII elements, diatomic non-metals whose reactivity decreases down the group.”
Answer: D
Chlorine water is added to aqueous potassium bromide.
Describe the colour change.
Write the ionic equation for the reaction.
Explain why iodine does not react with aqueous potassium bromide.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | colourless to orange (pale yellow-green / colourless) to orange / yellow-brown (allow brown) B1 | 1 |
| (b) | Cl₂ + 2Br⁻ → 2Cl⁻ + Br₂ correct species B1 balanced B1 | 2 |
| (c) | iodine less reactive than bromine iodine is less reactive than bromine, so cannot displace it B1 | 1 |
Chlorine is used to treat water.
Explain why chlorine is added to drinking water.
Describe the test for chlorine gas.
Predict the state and colour of astatine at room temperature.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | kills bacteria to kill bacteria/microorganisms B1 | 1 |
| (b) | damp litmus bleached damp blue litmus turns red then is bleached (white) B2 | 2 |
| (c) | black solid solid B1 black B1 | 2 |
Chlorine, bromine and iodine are halogens.
Describe the colours and states of chlorine, bromine and iodine at room temperature.
Describe the trend in reactivity down Group VII.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | pale green gas; red-brown liquid; grey-black solid chlorine: pale yellow-green gas B1 bromine: red-brown liquid B1 iodine: grey-black solid B1 | 3 |
| (b) | decreases reactivity decreases down the group B1 | 1 |
Halogens react with metals to form halides.
Write a balanced equation for the reaction of sodium with chlorine.
Explain, in terms of electrons, why reactivity decreases down Group VII.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 2Na + Cl₂ → 2NaCl correct formulae B1 balanced B1 | 2 |
| (b) | outer shell further, harder to gain electron the outer shell is further from the nucleus/more shielding B1 so an electron is attracted/gained less easily B1 | 2 |
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