DP Chemistry (first assessment 2025)
Question 19M.1A.SL.TZ2.20
| Date | May 2019 | Marks available | [Maximum mark: 1] | Reference code | 19M.1A.SL.TZ2.20 |
| Level | SL | Paper | 1A | Time zone | TZ2 |
| Command term | Question number | 20 | Adapted from | N/A |
20.
[Maximum mark: 1]
19M.1A.SL.TZ2.20
What is the major reason why the pH of unpolluted rain is less than 7?
A. methane
B. carbon dioxide
C. nitrogen oxides
D. sulfur dioxide
[1]
Markscheme
B
Examiners report
This was one of the challenging questions on the paper. 58 % of the candidates identified carbon dioxide as the cause of acidity in unpolluted rain. The rest mainly chose either nitrogen oxides (option C) or sulfur dioxide (option D), the causes of acidity in polluted rain.
Syllabus sections
Structure 3. Classification of matter » Structure 3.1—The periodic table: Classification of elements » Structure 3.1.5—Metallic and non-metallic properties show a continuum. This includes the trend from basic metal oxides through amphoteric to acidic non-metal oxides. Deduce equations for the reactions with water of the oxides of group 1 and group 2 metals, carbon and sulfur.