GCSE CHEMISTRY Foundation Tier Paper 2

Materials For this paper you must have: • a ruler • a scientific calculator • the periodic table (enclosed) Instructions • Use black ink or black ball-point pen. • Pencil should only be used for drawing. • Fill i ...

Materials For this paper you must have: • a ruler • a scientific calculator • the periodic table (enclosed) Instructions • Use black ink or black ball-point pen. • Pencil should only be used for drawing. • Fill in the boxes at the top of this page. • Answer all questions in the spaces provided. Do not write outside the box around each page or on blank pages. • If you need extra space for your answer(s), use the lined pages at the end of this book. Write the question number against your answer(s). • Do all rough work in this book. Cross through any work you do not want to be marked. • In all calculations, show clearly how you work out your answer. Information • The maximum mark for this paper is 100. • The marks for questions are shown in brackets. • You are expected to use a calculator where appropriate. • You are reminded of the need for good English and clear presentation in your answers. Please write clearly in block capitals. Centre number Candidate number Surname Forename(s) Candidate signature I declare this is my own work. GCSE CHEMISTRY Foundation Tier Paper 2 F2 *02* IB/M/Jun21/8462/2F Do not write outside the 0 1 This question is about the Earth’s atmosphere. box 0 1 . 1 How long ago was the Earth formed? [1 mark] Tick () one box. 4.6 billion years ago 4.6 million years ago 4.6 thousand years ago Table 1 shows the percentages of gases in the atmospheres of Mars and Earth today. Table 1 Gas Percentage of gas in atmosphere (%) Mars Earth Carbon dioxide 95.97 0.04 Nitrogen 1.89 78.09 Oxygen 0.15 20.95 Other gases 1.99 X 0 1 . 2 Calculate the percentage X of other gases in the Earth’s atmosphere. Use Table 1. [1 mark] X = %3 *03* Turn over ► IB/M/Jun21/8462/2F Do not write outside the The atmosphere of the early Earth is thought to have been similar to the atmosphere box of Mars today. The percentages of nitrogen and of oxygen in the Earth’s atmosphere today have changed from the percentages in the Earth’s early atmosphere. 0 1 . 3 Draw one line from each gas to the change in the percentage of that gas. Use Table 1. [2 marks] 0 1 . 4 The percentage of carbon dioxide in the Earth’s early atmosphere decreased. Which two processes caused this decrease? [2 marks] Tick () two boxes. Carbon dioxide dissolving in sea water Combustion of fossil fuels Farming of animals Formation of sedimentary rocks Volcanoes releasing carbon dioxide Gas Change in percentage of gas Nitrogen Oxygen Increased by about 4 times Increased by about 21% Increased by about 40 times Increased by about 96%4 *04* IB/M/Jun21/8462/2F Do not write outside the 0 1 . 5 Photosynthesis also decreased the percentage of carbon dioxide in the Earth’s box early atmosphere. Photosynthesis increased the percentage of another gas. Complete the word equation for photosynthesis. [2 marks] + water → glucose + 0 1 . 6 Complete the sentence. [1 mark] Scientists are not certain about the percentages of gases in the Earth’s early atmosphere because there is a lack of . 95 *05* Turn over ► IB/M/Jun21/8462/2F Do not write outside the Turn over for the next question box DO NOT WRITE ON THIS PAGE ANSWER IN THE SPACES PROVIDED6 *06* IB/M/Jun21/8462/2F Do not write outside the 0 2 This question is about water. box A student investigated the concentration of salt in sea water. This is the method used. 1. Filter the sea water to remove sand. 2. Measure the mass of an empty evaporating dish. 3. Measure 50 cm3 of sea water into the evaporating dish. 4. Heat the evaporating dish and sea water. 5. Evaporate the sea water to dryness. 6. Measure the mass of the evaporating dish and salt