DP Chemistry (first assessment 2025)
Question 20N.2.SL.TZ0.9f(ii)
| Date | November 2020 | Marks available | [Maximum mark: 2] | Reference code | 20N.2.SL.TZ0.9f(ii) |
| Level | SL | Paper | 2 | Time zone | TZ0 |
| Command term | Compare and contrast | Question number | f(ii) | Adapted from | N/A |
f(ii).
[Maximum mark: 2]
20N.2.SL.TZ0.9f(ii)
(f(ii))
Methane is another greenhouse gas. Contrast the reasons why methane and carbon dioxide are considered significant greenhouse gases.
[2]
Markscheme
carbon dioxide is highly/more abundant «in the atmosphere» ✔
methane is more effective/potent «as a greenhouse gas»
OR
methane/better/more effective at absorbing «radiation»
OR
methane has greater greenhouse factor
OR
methane has greater global warming potential/GWP✔
Accept “carbon dioxide contributes more to global warming” for M1.
Examiners report
We received many good answers, but it was worrying the number of students that still provided general and shallow comments. Of the 3 contrast question this had the best response.
Syllabus sections
Reactivity 1. What drives chemical reactions? » Reactivity 1.3—Energy from fuels » Reactivity 1.3.3—Fossil fuels include coal, crude oil and natural gas, which have different advantages and disadvantages. Evaluate the amount of carbon dioxide added to the atmosphere when different fuels burn. Understand the link between carbon dioxide levels and the greenhouse effect.