DP Chemistry (first assessment 2025)
Question 20N.1A.SL.TZ0.9
| Date | November 2020 | Marks available | [Maximum mark: 1] | Reference code | 20N.1A.SL.TZ0.9 |
| Level | SL | Paper | 1A | Time zone | TZ0 |
| Command term | Deduce | Question number | 9 | Adapted from | N/A |
9.
[Maximum mark: 1]
20N.1A.SL.TZ0.9
Which formula is correct?
A.
B.
C.
D.
[1]
Markscheme
C
Examiners report
64% of candidates picked the correct formula for ammonium phosphate with (NH4)2PO4 being the incorrect answer chosen most frequently. NH4PO4 or (NH4)3(PO4)2 was rarely selected.
Syllabus sections
Structure 2. Models of bonding and structure » Structure 2.1—The ionic model » Structure 2.1.2—The ionic bond is formed by electrostatic attractions between oppositely charged ions. Deduce the formula and name of an ionic compound from its component ions, including polyatomic ions. Binary ionic compounds are named with the cation first, followed by the anion. The anion adopts the suffix “ide”. Interconvert names and formulas of binary ionic compounds.