The Atmosphere and FuelsIB MYP Chemistry: Topic test

1. 1
   A technician in Santiago fills a 500 cm³ clean, dry container with outdoor air to calibrate an instrument. Outdoor air is a mixture of several gases.

   (a)

   Which two gases make up most of the dry air in the container?

   [1 mark]

   • AOxygen and carbon dioxide
   • BNitrogen and oxygen
   • CNitrogen and carbon dioxide
   • DOxygen and argon

   (b)

   The technician uses dry air rather than ordinary outdoor air. Which gas has been removed from the sample?

   [1 mark]

   • AArgon
   • BNitrogen
   • CWater vapour
   • DOxygen

   (c)

   Dry air contains about 21% oxygen by volume. Calculate the volume of oxygen in the 500 cm³ sample. Show your working.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   Planetary scientists compare the atmospheres of three rocky planets. The atmospheres of Venus and Mars are both about 95% carbon dioxide. Earth's atmosphere is about 0.04% carbon dioxide and about 21% oxygen. Earth is the only one of the three with liquid oceans and living organisms. Scientists think Earth's early atmosphere was much more like that of Venus and Mars, with plenty of carbon dioxide and water vapour but almost no oxygen.

   (a)

   Which process released most of the oxygen now in Earth's atmosphere?

   [1 mark]

   • APhotosynthesis by algae and plants
   • BRespiration by animals
   • CBurning of fossil fuels
   • DErupting volcanoes

   (b)

   What happened to most of the water vapour in the early atmosphere as the Earth cooled?

   [1 mark]

   • AIt escaped into space
   • BIt reacted with nitrogen
   • CIt was absorbed by plants
   • DIt condensed to form the oceans

   (c)

   Explain how the percentage of carbon dioxide in Earth's atmosphere decreased over time.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A catering company in Marrakesh cooks for a wedding using portable stoves that burn butane gas. A cook sets up a stove inside a large tent and closes all the tent flaps because of a cold wind. After an hour two of the staff feel dizzy and have headaches, and the flame on the stove has turned yellow and is leaving black marks on the pans.

   (a)

   Describe the products of complete combustion of butane and give a test for the gas that turns limewater milky.

   [3 marks]

   (b)

   Explain why the staff became ill and why the flame turned yellow.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A coal-fired power station near Katowice in Poland burns coal that contains sulfur. Downwind, a lake has become more acidic, fish numbers have fallen and limestone statues in the town square are being worn away. The power station provides about 40% of the region's electricity and employs 1,500 people. The government is considering replacing it with a gas-fired power station that burns natural gas, which contains almost no sulfur.

   (a)

   Explain how burning coal in the power station can lead to the damage described around Katowice.

   [6 marks]

   (b)

   Evaluate the government's proposal to replace the coal-fired power station with a gas-fired one. Consider the environmental, economic and social effects and give a justified conclusion.

   [6 marks]

   Total for question 4: 12 marks

5. 5
   A cyclist in Hanoi records how she feels while riding through the busy centre of the city. The streets are full of petrol motorbikes. An air quality app reports high levels of particulates and nitrogen oxides, and she often coughs after a ride.

   (a)

   How are nitrogen oxides formed in a motorbike engine?

   [1 mark]

   • ANitrogen and oxygen from the air react at the high temperature in the engine
   • BNitrogen in the petrol burns in the engine
   • CCarbon monoxide reacts with water in the exhaust
   • DPetrol undergoes incomplete combustion

   (b)

   Which statement about particulates is correct?

   [1 mark]

   • AThey cause acid rain by dissolving in rainwater
   • BThey are tiny solid particles that can damage the lungs when breathed in
   • CThey are the main gas that traps heat in the atmosphere
   • DThey are a colourless, odourless gas that stops blood carrying oxygen

   (c)

   Suggest one way the city could reduce air pollution from road transport and explain how it would help.

   [2 marks]

   Total for question 5: 4 marks

6. 6
   Farmers in Argentina keep millions of cattle, and rice growers in Vietnam flood their fields. Both activities release methane into the atmosphere. Methane is a greenhouse gas, and its percentage in the air has risen since 1800. Some people say that one hot summer shows the climate is changing, but climate scientists say they need much more evidence than that.

   (a)

   Which two other gases in the atmosphere are greenhouse gases?

   [1 mark]

   • ANitrogen and oxygen
   • BArgon and nitrogen
   • CCarbon dioxide and water vapour
   • DOxygen and argon

   (b)

   Which observation is the best evidence that the climate is changing, rather than that one summer was unusually hot?

   [1 mark]

   • AA heatwave in Argentina that lasted two weeks
   • BA very cold winter in Vietnam in one year
   • CA news report that a farmer saw less rain this year
   • DA rise in average global temperature measured at many stations over several decades

   (c)

   Explain how the increase in methane in the atmosphere contributes to climate change.

   [2 marks]

   Total for question 6: 4 marks

7. 7
   A student in Chennai notices that the flame of a Bunsen burner in the school laboratory is blue when the air hole is open and yellow when the air hole is closed. The yellow flame leaves a black deposit on glassware. She decides to investigate this.

   (a)

   Write a hypothesis for the effect of the air hole on the flame and explain it using scientific knowledge.

   [3 marks]

   (b)

   Describe a method to compare how much soot is produced with the air hole open and closed. Include how you would keep the test fair and one safety precaution.

   [4 marks]

   Total for question 7: 7 marks

8. 8
   Brazil has many cars that run on ethanol made from sugar cane instead of petrol, which is made from crude oil. Petrol is a fossil fuel. Growing sugar cane takes up a lot of farmland, and some farmers have cleared forest to plant it. The government of another country is deciding whether to follow Brazil and switch most of its cars to ethanol.

   (a)

   Explain how burning fossil fuels such as petrol in cars contributes to climate change.

   [6 marks]

   (b)

   Evaluate the government's decision to switch most cars to ethanol. Consider the environmental and economic effects and give a justified conclusion.

   [6 marks]

   Total for question 8: 12 marks

End of questions