Chemistry Past Paper C1
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What is the supporting evidence for Pangea?
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- Similar species. - Same fossil records. - Similar rocks. - Continents look like 'jigsaw'.
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What is the earth's crust made of?
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The crust & upper mantle.
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What is the evidence that the tectonic plates are moving?
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1. Same fossils in different continents, they must have joined at some point. 2. Earthquakes occur when tectonic plates move and collide.
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What causes the plates to move?
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convection currents
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What percentages of which gases compose the atmosphere?
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78% *Nitrogen* 21% *Oxygen* 1% Other gases
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Which environmental problem does sulphur dioxide create?
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Acid Rain
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How could acid rain be reduced in coal-fired power stations?
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Use flue gas desulphurisation which uses limestone powder to neutralise the acid gases
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*Combustion of methane* methane + ...... ->carbon dioxide + .....
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methane + water -> carbon dioxide + water
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Why should excess carbon dioxide be prevented from entering the atmosphere?
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Excess carbon dioxide reflects the sun's energy back to Earth and creates higher temperatures. This, in turn, creates rising sea levels & uncomfortable living conditions.
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How is carbon dioxide prevented from entering the atmosphere?
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Carbon dioxide is compressed and pumped back into the oil reservoir that the fossil fuels originally came from.
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What is an ore?
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An ore is a material that is worth while to be mined from the ground.
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Iron is produced by reacting iron oxide with carbon in a blast furnace, what type of reaction is this?
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A reduction reaction.
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What are the differences between pure iron and cast iron?
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Pure iron is soft and can be easily hammered into shape as its ions are regular and in rows, they slide over each other easily. In contrast, cast iron is an alloy and has different sized ions, discouraging the layers to side easily and therefore making the material harder.
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Why is recycling required for sustainable development?
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Without recycling, the material would eventually run out.
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What type of fat contains double carbon bonds?
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Unsaturated fats
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What is seen when bromine is shaken with an unsaturated fat?
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decolourises
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what is seen when bromine is shaken with a saturated fat?
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No change
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How are unsaturated fats hardened?
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Oils are hardened by passing them over a *nickel catalyst* at *60 degrees*.
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What is the name of the process that is used to detect the dyes in colourings?
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Chromatography
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How are alkanes separated using *fractional distillation*?
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Alkanes are heated and evaporated into a fractional column. Substances with a high melting point condense in lower fractions, substances with a lower melting point condense in higher fractions as it becomes cooler with height.
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What is the formula for methane?
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CH4
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What is the formula for ethane?
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C2 H6
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What is the formula for propane?
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C3 H8
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What is the formula for butane?
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C4 H10
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What are the properties of small molecules?
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- low boiling point - very volatile - highly flammable - Thin
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What are the properties of large molecules?
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- High boiling point - Not very volatile - Viscous - Doesn't ignite easily
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What is the formula for pentane?
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C5 H12
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What is the formula for hexane?
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C6 H14
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How can crude oils get over low supply of fuels?
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Create technology for low demand fractions. Crack larger fractions into smaller fractions. Create markets for low demand fractions.
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Why was Alfred Wegener not believed?
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1. His idea was different and couldn't be comprehended. 2. He had no proof.
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Something breaks down when heated, what is the name of the reaction?
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Thermal decomposition
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What does unsaturated mean?
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Double carbon bonds
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What effects do particulates have?
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Global dimming
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Explain the process of chromatography
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Small amounts of mixture are added to a piece of paper, stationed upright. Different substances move up the paper at different speeds.
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Environmental benefits of using biofuels
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Biofuel is said to be carbon neutral as although it turns fuel into CO2 when combusted, it photosynthesises and reduces CO2 when growing. Furthermore, it is a sustainable fuel.
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How is cracking carried out?
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Passed over a nickel catalyst at 60 degrees.
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What is the formula for an alkane?
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C2 H6
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Alkanes are ......
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Alkanes are saturated.
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Alkenes are ......
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Alkenes are unsaturated.
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Name the polymer made from ethene
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polythene
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Why does cracking have a carbon cost?
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Carbon dioxide is produced during the process by combustion.
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How does the number of carbon atoms in a hydrocarbon affect its boiling point?
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Higher carbon count = higher boiling point
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What is an element?
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A material made of one single atom type.
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How are earthquakes caused?
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Tectonic plates collide and radiate large shockwaves into their tectonic regions.
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Explain the problems with predicting earthquakes
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Scientists cannot view activity under the crust or measure the forces.
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When methane is burned, the waste gases contain Carbon dioxide and nitrogen, why?
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Nitrogen was fed into the kiln as a part of the air.
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Why may an alternative fuel be used?
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- More efficient. - More cost effective. - Less strenuous on resources.
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Why does Sudan 1 not have an E number?
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E number's are only awarded to safely checked substances.
