Changes to the Earth and its atmosphere

1. Starting with the centre of the Earth, what is the correct order for the layers of the Earth?

Core, mantle, crust
Mantle, core, core
Core, crust, mantle

2. What causes tectonic plates to move?

Convection currents in the mantle
Strong winds in the tropics
Sea water currents in the oceans

3. At what rates do tectonic plates move?

A few centimetres per year
A few metres per year
A few kilometres per year

4. Which is the most abundant gas in the atmosphere?

Oxygen
Nitrogen
Carbon dioxide

5. Which was the most abundant gas in the early atmosphere?

Oxygen
Nitrogen
Carbon dioxide

6. What is the approximate percentage of oxygen in the atmosphere today?

100 per cent
80 per cent
20 per cent

7. What caused the proportion of oxygen in the atmosphere to increase?

Respiration
Photosynthesis
Volcanic activity

8. Which of the following is a reason for the decrease in carbon dioxide in the Earth's atmosphere?

Its reaction with oxygen
It condensed to form the oceans
It became locked up in fossil fuels and sedimentary rocks

9. Why is helium used in balloons?

It is less dense than air
It is more dense than air
It has the same density as air

10. Why is neon used in neon lights?

It is coloured
It gives off light when electricity passes through it
It burns in air with a red flame

11. Why are the noble gases used in light bulbs?

They stop the filament burning
They make the bulb lighter to carry
They are cheap