| Date | November 2009 | Marks available | 2 | Reference code | 09N.3.hl.TZ0.E3 |
| Level | HL | Paper | 3 | Time zone | TZ0 |
| Command term | Outline | Question number | E3 | Adapted from | N/A |
Question
The concentration of some pollutants in a city was measured over a 24 hour period. The results are shown below.
Outline the cause of the increase in NO levels between 5 and 8 am.
Markscheme
NO produced from cars engines increases during morning rush hour;
NO produced by high temperature combination of nitrogen and oxygen (in engine);
Examiners report
In (a), most candidates scored M1, but reference to high temperature was often omitted.
