6 Do not write outside the box GK84796Jun12CH1HP 10 4 Venus is

6 do not write outside the box gk84796jun12ch1hp 10 4

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10 Do not write outside the box G/K84796/Jun12/CH1HP (10) 4 Venus is often compared to the Earth. The Earth’s early atmosphere was mainly carbon dioxide like the atmosphere of Venus today. Atmosphere of Earth today Atmosphere of Venus today Gas Percentage (%) Gas Percentage (%) Nitrogen 78 Nitrogen 3.5 Oxygen 21 Oxygen A trace Carbon dioxide 0.04 Carbon dioxide 96 4 (a) Give two reasons why the percentage of carbon dioxide decreased in the Earth’s early atmosphere. ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ (2 marks) 4 (b) In the 1950s two scientists, Miller and Urey, investigated the origin of life on Earth. Miller and Urey used the gases that they believed were in the Earth’s early atmosphere and used water to represent the oceans. The gases they used were methane (CH 4 ), ammonia (NH 3 ) and hydrogen (H 2 ). A continuous electrical spark was used to simulate lightning storms. After one week the Miller-Urey experiment had produced amino acids. Amino acids are essential to life. The simplest amino acid is glycine (aminoethanoic acid). H CC N H HO HO H
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11 Do not write outside the box G/K84796/Jun12/CH1HP Turn over (11) The apparatus used in the Miller-Urey experiment is shown in the diagram. Direction of water vapour circulation Cold water Condenser Trap Electrical spark (lightning) H 2 O, CH 4 , NH 3 , H 2 Gases (early atmosphere) Cooled water (containing organic compounds) + Heat source Water (ocean) Use the information in the diagram and on page 10 to answer these questions. 4 (b) (i) Miller and Urey used methane, ammonia and hydrogen for the Earth’s early atmosphere. Suggest why. ............................................................................................................................................ ............................................................................................................................................ (1 mark) 4 (b) (ii) The experiment provides only weak evidence of how amino acids formed on Earth. Suggest two reasons why. ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ (2 marks) ____ 5
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12 Do not write outside the box G/K84796/Jun12/CH1HP (12) 5 Calcium carbonate is found in limestone. Limestone is used as a building material. Limestone is also used to make calcium oxide and calcium hydroxide. 5 (a) Limestone is heated to make calcium oxide. 5 (a) (i) Calcium oxide reacts with a substance to produce calcium hydroxide.Name the substance............................................................................................................................................. Balance the chemical equation for the reaction of calcium carbonate with hydrochloric acid. CaCO 3 + HCl CaCl 2 + CO 2 + H 2 O (1 mark) 5 (b) (ii) Buildings made from limestone are affected by the products from burning fossil fuels containing sulfur. Explain why. ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ (2 marks)
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13 Do not write outside the box G/K84796/Jun12/CH1HP (13) 5 (c) When a mixture of limestone and clay is heated in a rotary kiln cement is produced. Burning a mixture of methane and air heats the kiln. Clay does not decompose in the kiln. Rotary kiln Mixture of gases Mixture of limestone and clay Mixture of methane and air Cement 5 (c) (i) Carbon dioxide is one of the main gases in the mixture of gases coming out of the kiln.
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