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| Question | Answer |
| Name the two main gases that make up the Earth's atmosphere today. | Nitrogen and Oxygen. |
| Explain why today's atmosphere is different from the Earth's early atmosphere. | The carbon dioxide dissolved into the oceans where developed organisms took them in. Green plants photosynthesised and also took in this carbon dioxide. They produced oxygen which caused the oxygen levels to gradually rise. |
| How were the oceans formed? | Water vapour from volcanoes condensed. |
| List three ways in which human activity is changing the atmosphere. | By burning fossil fuels, deforestation and livestock farming. |
| Apart from humans, what else is changing the atmosphere? | Volcanic eruptions. |
| Describe how you could investigate the proportion of oxygen in the air. | Heat an excess of copper in a tube and pass air over it using two syringes and using the markers on them to tell how much oxygen has been used up. |
| Name the three types of rock. | Sedimentary, metamorphic and igneous. |
| What type of rock is marble and how is it formed? | Marble is a metamorphic rock and is formed by chalk or limestone being broken down by very high temperatures and reforming as small crystals in the ground. |
| What type of rock is chalk? | Sedimentary. |
| Describe the difference in the way the crystals of extrusive and intrusive rocks form. | Extrusive rocks form small crystals as they cool quickly above ground while intrusive rocks form big crystals as they cool slowly underground. |
| Name three building materials made from limestone. | Limestone blocks, cement and concrete. |
| Give two positive and two negative points about limestone quarrying. | Provides jobs for the local people and is used to make lots of useful things (dyes, medicine etc.) Damages the landscape with big, ugly holes and destroys the natural habitats of animals and birds. |
| What is thermal decomposition? | It is a reaction in which one substance breaks down when heated to form two or more new substances. |
| Write down the symbol equation showing the thermal decomposition of limestone. | CaCO3 -> CaO + CO2 |
| How could you test for carbon dioxide in a thermal decomposition reaction? | Bubble the carbon dioxide through limewater and see if it turns milky. |
| Write down the symbol equation for the thermal decomposition reaction of zinc carbonate. | ZnCO3 -> ZnO + CO2 |
| What product can be made by adding water to calcium oxide and why is it useful? | Calcium hydroxide. It's useful for neutralising acidic soil. |
| Are atoms lost and made in a reaction or just rearranged? | Atoms are just rearranged. |
| If you carry out a reaction in a sealed container, what would you notice about the mass of f the reactants and products? | They would be the same. |
| What is a precipitate? | It is the insoluble solid formed in a solution when two solutions react. |
| What does the number in front of a formula apply to? | It applies to the entire formula. |
| What is the state symbol for 'dissolved in water'? | (aq) |
| Give the meaning of this symbol. | Toxic. |
| Do acids have a pH greater or less than 7? | Less than. |
| Name the acid produced by the stomach. | Hydrochloric acid. |
| How do indigestion tablets work? | They contain bases such as calcium carbonate which neutralise the excess stomach acid which causes indigestion. |
| What do you get when you react an acid with a metal oxide. | Salt and water. |
| Write a balanced symbol equation for the reaction of hydrochloric acid with sodium carbonate. | 2HCl + Na2CO3 -> 2NaCl + H2O + CO2 |
| Is the anode positive or negative? | Positive. |
| Are anions or cations attracted to the anode? | Anions. |
| How would you test for hydrogen gas? | Put a lighted splint in the test tube and if a squeaky pop is made then there is hydrogen. |
| Name a product of the electrolysis of salt. | k |
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