| Date | May 2015 | Marks available | 1 | Reference code | 15M.3.sl.TZ2.19 |
| Level | SL | Paper | 3 | Time zone | TZ2 |
| Command term | Identify | Question number | 19 | Adapted from | N/A |
Question
Climate change is a current global topic of debate.
Water and carbon dioxide are greenhouse gases present in significant quantities in the atmosphere. Identify one other greenhouse gas and its source.
Suggest the two factors that influence the relative greenhouse effect of a gas.
Markscheme
Any one of:
Do not accept other gases such as SOx and NOx – generally reckoned to be insignificant.
Any two for [1] of:
abundance/concentration (in atmosphere)
strength/intensity/power of IR absorbance / ability to absorb heat radiation
lifetime/duration / rate of depletion/decomposition in atmosphere;
Examiners report
Many candidates identified another greenhouse gas with methane and CFCs being the most popular answers.
Most candidates identified abundance as a factor which influences the relative greenhouse effect of a gas but failed to identify a second factor. Few candidates were able to clearly articulate the effect and the consequences of increasing amounts of greenhouse gases. In addition, there was often confusion with ozone depletion and acid rain.
Many candidates identified another greenhouse gas with methane and CFCs being the most popular answers.
Most candidates identified abundance as a factor which influences the relative greenhouse effect of a gas but failed to identify a second factor. Few candidates were able to clearly articulate the effect and the consequences of increasing amounts of greenhouse gases. In addition, there was often confusion with ozone depletion and acid rain.
