Chemistry 9701 · 25 Equilibria
25.1 Acids and bases
Define conjugate pairs, calculate pH/Ka/pKa/Kw, explain buffer action and solubility product (Ksp), and perform related calculations.
- Questions
- 94
- Years
- 2015–2026
- Multiple choice
- 16
- Written answer
- 78
- Average marks
- 10.7
Where this subtopic appears
- Paper 4variants 41, 42, 43, 4469
- Paper 1variants 11, 12, 1316
- Paper 5variants 51, 52, 537
- Paper 2variants 221
- Paper 3variants 351
Questions by year
| Year | Feb/March | May/June | Oct/Nov | Total |
|---|---|---|---|---|
| 2026 | – | 6 | – | 6 |
| 2023 | 1 | 3 | 2 | 6 |
| 2022 | 3 | 2 | 3 | 8 |
| 2021 | 1 | 6 | 5 | 12 |
| 2020 | 2 | 9 | 7 | 18 |
| 2019 | 2 | 3 | 4 | 9 |
| 2018 | 2 | 5 | 11 | 18 |
| 2017 | – | 3 | 3 | 6 |
| 2016 | 1 | 3 | 4 | 8 |
| 2015 | – | 3 | – | 3 |
