Greenhouse gases and global warming
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Greenhouse gases and global warming — Free MYP4 Chemistry Practice Questions

1QuestionSources of greenhouse gas emissionsConcept Practice
2 marks~3 minCriterion A
The diagram shows a molecule with a central carbon atom bonded to four hydrogen atoms in a tetrahedral arrangement.
a
Identify the molecule shown, giving its chemical formula. [1]
b
State one human-related activity that releases this molecule into the atmosphere. [1]
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Solutions

2QuestionSources of greenhouse gas emissionsAssessment Practice
5 marks~8 minCriterion D
A student investigates the hypothesis: "Methane (CH4_4) is a more potent greenhouse gas per molecule than carbon dioxide (CO2_2)." Infrared (IR) absorbance is measured for each pure gas at six concentrations using a fixed path length of 10 cm. CH4_4 is tested at 7.7 μm; CO2_2 at 15 μm.

Concentration (×1018\times 10^{18} molecules/cm3^3): 0.5, 1.0, 2.0, 3.0, 4.0, 5.0

Absorbance for CH4_4 (arbitrary units): 0.10, 0.20, 0.40, 0.60, 0.80, 1.00

Absorbance for CO2_2 (arbitrary units): 0.02, 0.04, 0.08, 0.12, 0.16, 0.20
a
Calculate the absorbance per molecule for CH4_4 and for CO2_2, using the data at 1.0×10181.0 \times 10^{18} molecules/cm3^3. [2]
b
Using your results from (a), deduce the ratio of IR absorbance per molecule for CH4_4 relative to CO2_2, and state whether the data supports the hypothesis. [1]
c
Evaluate the reliability of this experiment as evidence for the real-world greenhouse potency of CH4_4 compared with CO2_2. Identify two limitations and suggest one improvement. [2]
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Solutions

3QuestionGreenhouse effect mechanismAssessment Practice
6 marks~9 minCriterion C

Analyze the following data that presents the infrared (IR) absorption strength and atmospheric concentration of four greenhouse gases.

Gas: CO2, CH4, H2O, N2O

Concentration (ppm): 415, 1.9, 4000 (variable), 0.33

IR absorption at 10 μm (relative units): 0.8, 0.5, 1.0, 0.2

a
Identify the anomaly in the relationship between atmospheric concentration and IR absorption strength based on the data provided. [2]
b
Explain why methane (CH4) absorbs IR radiation more efficiently per molecule than carbon dioxide (CO2), despite its lower concentration. In your response, refer to the molecular structure and vibrational modes of both gases. [3]
c
State one implication of this anomaly for the global warming potential (GWP) of methane compared to carbon dioxide. [1]
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Solutions

4QuestionSources of greenhouse gas emissionsAssessment Practice
6 marks~9 minCriterion B
The table below shows total annual greenhouse gas emissions (million tonnes of CO2\text{CO}_2-equivalent) for four countries in 2000 and 2020.

Country A — 2000: CO2\text{CO}_2 450, CH4\text{CH}_4 120, N2O\text{N}_2\text{O} 402020: CO2\text{CO}_2 380, CH4\text{CH}_4 110, N2O\text{N}_2\text{O} 50
Country B — 2000: CO2\text{CO}_2 600, CH4\text{CH}_4 200, N2O\text{N}_2\text{O} 602020: CO2\text{CO}_2 550, CH4\text{CH}_4 180, N2O\text{N}_2\text{O} 65
Country C — 2000: CO2\text{CO}_2 300, CH4\text{CH}_4 80, N2O\text{N}_2\text{O} 302020: CO2\text{CO}_2 280, CH4\text{CH}_4 75, N2O\text{N}_2\text{O} 35
Country D — 2000: CO2\text{CO}_2 520, CH4\text{CH}_4 150, N2O\text{N}_2\text{O} 502020: CO2\text{CO}_2 490, CH4\text{CH}_4 250, N2O\text{N}_2\text{O} 55
a
Describe the overall trend in CO2\text{CO}_2 emissions across all four countries from 2000 to 2020. [1]
b
Deduce which country shows an anomalous change in CH4\text{CH}_4 emissions. Support your answer with a calculated percentage change and a comparison with the other three countries. [3]
c
Analyse how an error in applying global warming potential (GWP) conversion factors could produce the anomaly identified in (b), and explain what effect correcting this error would have on the reported total emissions for that country. [2]

Solutions

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