Greenhouse effect and climate changeIB MYP Chemistry: Subtopic test

1. 1
   A science teacher in Nairobi explains that, without certain gases in the atmosphere, the average surface temperature of the Earth would be about −18 °C instead of the present 15 °C. Her class is learning which atmospheric gases cause this warming and how they work.

   (a)

   Which pair of gases are both greenhouse gases?

   [1 mark]

   • ANitrogen and oxygen
   • BCarbon dioxide and methane
   • CArgon and helium
   • DOxygen and hydrogen

   (b)

   What happens to the infrared radiation given out by the warm surface of the Earth?

   [1 mark]

   • AIt passes straight through the atmosphere into space unchanged
   • BIt is reflected back to the Sun by the ozone layer
   • CIt is changed into visible light by the oxygen in the air
   • DGreenhouse gases absorb some of it and re-emit it in all directions, including back towards the surface

   (c)

   Explain how greenhouse gases keep the Earth warmer than it would be without them.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   Scientists in Antarctica drill ice cores and analyse tiny air bubbles trapped in the ice. Air trapped around the year 1750 contained about 280 parts per million (ppm) of carbon dioxide. A mountain observatory in Hawaii now measures about 420 ppm. Over the same period, global average temperature records show a rise of about 1.1 °C.

   (a)

   Which statement is supported by the information given?

   [1 mark]

   • AThe concentration of carbon dioxide in the atmosphere has risen by about 140 ppm since 1750
   • BThe concentration of carbon dioxide has halved since 1750
   • CThe temperature rise of 1.1 °C proves that carbon dioxide is the only cause of climate change
   • DThe concentration of carbon dioxide has stayed the same since 1750

   (b)

   Why are ice cores useful to climate scientists?

   [1 mark]

   • AThey show the exact weather on every day in the past
   • BThey contain only methane, so they show how much methane farming produces
   • CTrapped air bubbles preserve samples of the ancient atmosphere, so past gas concentrations can be measured
   • DThey measure the current temperature of the Antarctic atmosphere

   (c)

   Describe two other types of evidence, apart from the data given, that scientists use to show that the climate is changing.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A student in Singapore investigates whether carbon dioxide traps heat. She fills one clear plastic bottle with air and an identical bottle with air containing extra carbon dioxide from a gas cylinder, and puts a thermometer in each. She shines the same 60 W lamp on both bottles from 30 cm away for 10 minutes and records the temperature each minute. She predicts that the bottle with extra carbon dioxide will warm up more. After 10 minutes, the temperature of the air-filled bottle has risen by 4.0 °C and that of the carbon dioxide bottle by 5.5 °C.

   (a)

   Identify the independent variable, the dependent variable and one control variable in the student's investigation.

   [3 marks]

   (b)

   Evaluate the student's investigation. In your answer, calculate the difference between the temperature rises, state whether the results support her prediction, give one weakness of the investigation, and suggest one improvement that would make her conclusion more reliable.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   The government of a large country has promised to cut its carbon dioxide emissions sharply by 2040. It currently burns coal, oil and gas to generate electricity and to run transport, and its ministers are debating how to keep the promise. One proposal is to replace coal-fired power stations with wind and solar farms. Another is to plant millions of trees.

   (a)

   Discuss the benefits and drawbacks of replacing coal-fired power stations with wind and solar farms.

   [6 marks]

   (b)

   A minister claims: "Planting trees will solve our climate problem on its own, so we can carry on burning fossil fuels." Evaluate this claim.

   [6 marks]

   Total for question 4: 12 marks

End of questions