1. M. Rahman C1 TOPIC 1 1) What is the approximate percentage of oxygen in Earth’s modern day atmosphere?. Answer 21 %

2. M. Rahman C1 TOPIC 1 2) Which gas has the largest percentage in Earth’s modern day atmosphere? Answer Nitrogen

3. M. Rahman C1 TOPIC 1 3) Which gas made up the majority of the Earth’s early atmosphere? Answer Carbon dioxide

4. M. Rahman C1 TOPIC 1 4) Where is much of the gas that once made up the Earth’s early atmosphere now located? Answer. It dissolved in oceans and was then taken up by marine organisms.

5. M. Rahman C1 TOPIC 1 5) What is the approximate percentage of carbon dioxide currently found in the atmosphere? Answer. 0.04 %

6. M. Rahman C1 TOPIC 1 6) Give three ways humans have contributed to the amount of CO 2 in the atmosphere Answer a)deforestation b)burning fossil fuels c)farming

7. M. Rahman C1 TOPIC 1 7) Which of the following activities is not a human activity that causes small changes to the atmosphere over time? a)deforestation b)burning fossil fuels c)volcanoes erupting d)farming Answer C) volcanoes erupting

8. M. Rahman C1 TOPIC 1 8) Which process was responsible for increasing the amount of oxygen in the atmosphere over time? Answer photosynthesis

9. M. Rahman C1 TOPIC 1 9) Which gas do plants take out of the atmosphere? carbon dioxide

10. M. Rahman C1 TOPIC 1 10) Which of the following gases are released by volcanoes? a)oxygen and nitrogen b)carbon dioxide and hydrogen c)oxygen only d)carbon dioxide and steam Answer d) carbon dioxide and steam

11. M. Rahman C1 TOPIC 1 11) Which of the following gases could be released when fossil fuels are burned? a)carbon dioxide and carbon monoxide b)carbon dioxide and oxygen c)ammonia and nitrogen d)nitrogen and oxygen Answer a) carbon dioxide and carbon monoxide

12. M. Rahman C1 TOPIC 1 12) How where oceans formed (3) Answer 1) Water vapour released from volcanoes 2)Water vapour condensed as the earth cooled. 3) Rain falls to fill up the hollows in the crust.

13. M. Rahman C1 TOPIC 1 13) Describe why burning fossil is harmful to the earth and its environment (2). Answer Increases amount of CO 2 in the atmosphere,; carbon dioxide is a green house gas, which causes global warming; greenhouse gases prevent heat from leaving the earths atmosphere; Trapped heat causes the earth temperature to rise..

14. M. Rahman C1 TOPIC 1 14) Billions of years ago, which gas was in the greatest amount? Answer Carbon dioxide

15. M. Rahman C1 TOPIC 1 15) Give the origins of one piece of evidence that scientist have collected to explain the composition of the earths atmosphere Answer Antarctic ice cores-difference layers contain different amount of each gas. Each layer represents a different time. or Oxygen locked in rocks.

16. M. Rahman C1 TOPIC 1 16) In todays atmosphere, which gas is present that was either in very small amounts or not at all Answer Oxygen

17. M. Rahman C1 TOPIC 1 17) Explain how the levels of oxygen has changed over billions of years (2). Answer Primitive green plants evolved using carbon dioxide (1) and released oxygen by photosynthesis (1).

18. M. Rahman C1 TOPIC 1 18) Describe how carbon gets locked into sedimentary rocks (2). Answer Carbon dioxide dissolved in sea water reacts with other chemicals to form calcium carbonate and calcium hydrogen carbonate (1). The shells of dead sea creatures accumulate and are transformed into sedimentary rocks (1).

19. M. Rahman C1 TOPIC 1 19) Describe how the levels of carbon dioxide in the atmosphere in the earths early atmosphere was reduced(2). Answer By photosynthesis (1) and by dissolving in the oceans (1).

20. M. Rahman C1 TOPIC 1 20) Name three ways humans are changing the atmosphere. Answer 1)Burning of fossil fuels 2) deforestation 3) livestock farming

21. M. Rahman C1 TOPIC 1 21) Answer Iron reacts with oxygen to from iron oxide. Reaction uses up oxygen and total amount of air reduces. The water rises inside the tube to fill up the gap 100 mm 79 mm iron 1)Explain how the above experiment could be used to determine the amount of oxygen in the atmosphere (4 marks)

22. M. Rahman C1 TOPIC 1 20) Answer 300 x 0.21=63 mm (1) 300-63= 237mm (2) 22) 300 mm ? mm iron 1)If the atmosphere contains 21 % oxygen, what will the final reading be. Show your working out. (3 marks)

23. M. Rahman C1 TOPIC 1 20) Answer 750-592 =158 (1) 158/750= 0.21 (1) 0.21 x 100 = 21 % 23) 750 mm 592 mm iron 1) Show that the percentage of oxygen in the atmosphere is 21 %.

24. M. Rahman C1 TOPIC 1 24) Answer Copper reacts with oxygen to from copper oxide. Reaction uses up oxygen and total amount of air reduces. The gap between the syringes should reduce. Compare reading before heating with after heating. 1)Explain how the above experiment could be used to determine the amount of oxygen in the atmosphere (4 marks)

25. M. Rahman C1 TOPIC 1 25) Answer Iron + Oxygen ----  Iron Oxide Iron reacts with oxygen to produce iron oxide. Write the word equations.