Question 1 Medium
Balance the equation: __ K + __ H₂O → __ KOH + __ H₂. Give the numbers in order, separated by commas.
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Answer: 2, 2, 2, 1
- H: 2 H₂O gives 4 H, so 2 KOH and 1 H₂ needs 2 + 2.
- 2 K, 2 H₂O, 2 KOH, 1 H₂.
Groups 0, 1 and 7: GCSE Combined Science Chemistry practice questions
A second set of questions on groups 0, 1 and 7. They are different from the ones on the topic page. Try each, then open the answer and compare your working.
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Question 2 Medium
Chlorine is bubbled through potassium bromide solution. What colour does the solution turn?
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Answer: orange
- Chlorine displaces bromine.
- Bromine solution is orange.
Question 3 Medium
Bromine solution is added to potassium iodide solution. Does a reaction happen? Answer yes or no.
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Answer: yes
- Bromine is more reactive than iodine.
- So it displaces iodine and a reaction happens.
Question 4 Medium
Name the compound made when sodium reacts with chlorine.
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Answer: sodium chloride
- A metal and a halogen make a metal halide.
- It is sodium chloride.
Question 5 Hard
Write the balanced equation for chlorine reacting with potassium iodide solution. Do not use state symbols.
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Answer: Cl₂ + 2KI → 2KCl + I₂
- Chlorine displaces iodine.
- Cl₂ + 2KI → 2KCl + I₂
Question 6 Hard
Francium is below caesium in Group 1. Predict whether it is more or less reactive than caesium.
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Answer: more reactive
- Reactivity increases down Group 1.
- So francium is more reactive.
Question 7 Hard
Astatine is below iodine in Group 7. Predict its state at room temperature.
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Answer: solid
- Melting and boiling points increase down the group.
- Iodine is already a solid, so astatine is a solid.
Question 8 Hard
Explain why fluorine is more reactive than chlorine.
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Answer: the outer shell is closer to the nucleus so an electron is gained more easily
- A halogen gains one electron.
- In fluorine the outer shell is closer to the nucleus, so the attraction is stronger and the electron is gained more easily.
Question 9 Medium
Why are noble gases unreactive? They have a full … of electrons.
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Answer: outer shell
- A full outer shell means no need to gain, lose or share electrons.
- So they are unreactive.
Quick checks
Short questions with options. Choose one before you open the answer.
Check 1
Why are the noble gases unreactive?
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They have full outer shells of electrons.
Check 2
What does monatomic mean?
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Existing as single atoms.
Check 3
What happens to the boiling points of the noble gases down the group?
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They increase.
Check 4
Name a use of helium.
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In balloons, because it is less dense than air and not flammable.
Check 5
How many outer electrons do alkali metals have?
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One.
Check 6
Why are alkali metals stored in oil?
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They react with air and water.
Check 7
What do alkali metals make when they react with water?
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A metal hydroxide and hydrogen.
Check 8
Why is the solution from alkali metal and water alkaline?
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It contains hydroxide ions.
Check 9
How does the melting point change down Group 1?
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It decreases.
Check 10
How does reactivity change down Group 1?
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It increases.
Check 11
Why does reactivity increase down Group 1?
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The outer electron is further from the nucleus and is lost more easily.
Check 12
What are the formulae of the halogen molecules?
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F₂, Cl₂, Br₂ and I₂.
Check 13
What is the colour and state of bromine at room temperature?
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A red-brown liquid.
Check 14
How does reactivity change down Group 7?
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It decreases.
Check 15
What charge is on a halide ion?
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1−.
Check 16
What is a displacement reaction between halogens?
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A more reactive halogen takes the place of a less reactive one in its salt.
Check 17
Why does chlorine displace bromine from potassium bromide?
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Chlorine is more reactive than bromine.
Check 18
Name a use of argon.
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Filling filament lamps, because it will not react with the hot filament.
Check 19
Which noble gas has the lowest boiling point?
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Helium.
Check 20
What is the charge on an alkali metal ion?
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1+.
Check 21
Which alkali metals float on water?
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Lithium, sodium and potassium.
Check 22
What colour flame does potassium give when it reacts with water?
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Lilac.
Check 23
What are the elements in Group 7 called?
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The halogens.
Check 24
What colour is chlorine gas?
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Pale green.
Check 25
What colour is iodine vapour?
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Purple.
Check 26
What does diatomic mean?
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Made of molecules with two atoms.
Check 27
Why are the noble gases inert?
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They have a full outer shell of electrons, so they do not need to gain, lose or share electrons.
Check 28
What is the trend in boiling point down Group 0?
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It increases as the atoms get bigger.
Keep going with Groups 0, 1 and 7
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