Lesson Y8-U01-L04

Y8-U01-L04 How Volcanoes Form and Erupt Quiz: KS3 Geography, Unit 7

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson Y8-U01-L04, How Volcanoes Form and Erupt: 20 multiple choice questions for the KS3 Geography (National Curriculum), Unit 7: Year 8: Restless Earth: Tectonic Hazards, written with Revision Ninja.

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The 20 questions

  1. What is magma?

    • Ice that melts from glaciers into rivers
    • Melted rock that has already flowed out onto the surface
    • Melted, runny rock found below the ground
    • Hot gas released from cracks in the crust

  2. What is lava?

    • Magma that has reached the surface and flowed out
    • Fine ash that settles on the ground after an eruption
    • Hot gas that escapes from cracks in the crust
    • Cold rock that has been pushed up from the mantle

  3. What is a vent?

    • A layer of ash that builds up on the volcano's slopes
    • The pipe inside a volcano that magma travels up
    • A chamber where magma cools into solid rock
    • The wide crater at the very top of a mountain

  4. What is a magma chamber?

    • A tunnel carved by rivers under the volcano
    • A layer of solid rock that blocks the vent
    • A cone of ash built up around the crater from years of small eruptions
    • A large pool of magma stored deep underground

  5. What does viscosity measure?

    • How far lava travels before it cools down
    • How much gas is dissolved inside a magma chamber
    • How hot a liquid is when it leaves a volcano
    • How thick and sticky a liquid is

  6. What is the crater of a volcano?

    • The pipe through which magma rises from the chamber
    • The layer of rock that forms the outer slope and holds the lava in place for centuries
    • The opening at the top where magma, ash and gas escape
    • The deep pool of magma stored below the volcano

  7. Roughly how hot is the mantle just below the crust?

    • Around 10°C
    • Over 1,000°C
    • Around 100°C
    • Around 50°C

  8. Which volcano in Italy is given as an example, with magma rising up a central vent?

    • Mount Fuji
    • Mount Everest
    • Mount Etna
    • Ben Nevis

  9. Put these eruption stages in the correct order.

    • Rising up the vent, erupting, melting in the mantle, collecting in the chamber
    • Melting in the mantle, collecting in the chamber, rising up the vent, erupting from the crater
    • Collecting in the chamber, melting in the mantle, erupting from the crater, rising up the vent
    • Erupting from the crater, rising up the vent, collecting in the chamber, melting in the mantle

  10. A volcano has runny, low-viscosity magma. Which kind of eruption is most likely?

    • Gentle lava flows that spread out over a wide area
    • A sudden collapse of the whole mountain at once
    • Explosive blasts of ash that fire rock into the air
    • Thick, sticky lava that stays piled near the crater

  11. A volcano has very sticky magma. Why is its eruption more dangerous?

    • Gas is trapped until the pressure bursts it out violently
    • Magma is so thin that it runs away from the vent
    • Gas escapes easily, so the pressure drops and the eruption is quiet
    • Sticky magma cools inside the vent, so no lava reaches the surface

  12. Why did Mount St Helens blow the side off the mountain?

    • Its magma chamber had very low pressure before the eruption
    • Its magma had high viscosity, trapping gas and building huge pressure
    • Its magma had low viscosity, letting lava flow down the slopes
    • Its surface rock was extremely hot before the eruption, which made the mountain collapse early

  13. Why does magma rise through the crust?

    • It is less dense than the solid rock around it, so it slowly floats upwards
    • It is pulled upwards by the energy of the Sun, which warms the rock on the surface of the ground
    • It is heavier than the rock, so it sinks through the crust
    • It is pushed sideways by ocean currents under the crust

  14. A pupil says magma and lava are the same thing. Which response is correct?

    • No, magma is ash and dust that falls from the sky, while lava is solid rock from the ocean floor
    • Yes, they are the same, but only lava is found underground
    • No, magma is underground, while lava is the same material once it erupts at the surface
    • Yes, but lava is always cold while magma is always hot

  15. Before an eruption, which stage most often causes tremors that warn people?

    • When gas leaves the crater with no warning at all
    • When rising magma forces its way up the vent and cracks the rock
    • When the mantle first melts the subducting plate
    • After the lava has cooled into solid rock, when the volcano has been quiet for many years

  16. Which feature lies at the bottom of the volcano cross-section?

    • The vent at the very top of the mountain
    • The magma chamber, where magma pools before it rises
    • The crater, where lava flows out across the slopes and the valleys below the volcano
    • The ash cloud that rises above the summit

  17. Why do explosive eruptions tend to occur at destructive boundaries?

    • The plates slide sideways, so pressure never builds up
    • Sticky magma from the melted plate traps gas, so pressure builds before it bursts out
    • Explosive eruptions only happen where runny lava flows gently
    • The plates are pulled apart, so gas escapes easily and the lava never becomes sticky at all

  18. Why does Iceland's lava flow so gently?

    • Its magma is extremely sticky, which holds back all of the gas
    • Its volcanoes are deep under the ocean, so lava cannot escape
    • Its lava is made of ice and cooled water, so it flows quietly down the slopes
    • Its runny magma lets gas escape easily, so pressure does not build dangerously

  19. Which evidence would best suggest that a volcano may be about to erupt?

    • The slopes of the mountain become gradually flatter over decades
    • The volcano's crater stays completely dry for many years
    • Earthquake tremors and gas release, as rising magma builds pressure underground
    • The volcano's summit becomes covered in fresh snow, which shows that pressure is building

  20. Why might two nearby volcanoes erupt in very different ways?

    • Their magmas can differ in viscosity and gas content, so their eruptions differ
    • The one with more snow always erupts more gently, because the snow cools the magma in the vent
    • They always have identical magma because they are close together
    • The one at a higher altitude always produces runnier magma

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