| Date | May 2019 | Marks available | 1 | Reference code | 19M.1.sl.TZ1.20 |
| Level | SL | Paper | 1 | Time zone | TZ1 |
| Command term | Question number | 20 | Adapted from | N/A |
Question
Which is not a source of oxides of sulfur and nitrogen?
A. burning coal
B. internal combustion engines
C. burning methane
D. volcanic eruptions
Markscheme
C
Examiners report
One teacher thought this was a tricky question if candidates did not think of impurities in the combustion. However, 64 % of candidates answered correctly.
