DP Chemistry (first assessment 2025)
Question 22M.1A.SL.TZ2.9
| Date | May 2022 | Marks available | [Maximum mark: 1] | Reference code | 22M.1A.SL.TZ2.9 |
| Level | SL | Paper | 1A | Time zone | TZ2 |
| Command term | State | Question number | 9 | Adapted from | N/A |
9.
[Maximum mark: 1]
22M.1A.SL.TZ2.9
Which statement best describes the intramolecular bonding in HCN (l)?
A. Electrostatic attractions between H+ and CN− ions
B. Hydrogen bonding
C. Van der Waals forces and hydrogen bonding
D. Electrostatic attractions between pairs of electrons and positively charged nuclei
[1]
Markscheme
D
Examiners report
The majority of the candidates thought the bonding in HCN is ionic (electrostatic attraction between H+ and CN- ions) rather than covalent. The description of covalent bonding was the second most commonly chosen response.
Syllabus sections
Structure 2. Models of bonding and structure » Structure 2.2—The covalent model » Structure 2.2.1—A covalent bond is formed by the electrostatic attraction between a shared pair of electrons and the positively charged nuclei. The octet rule refers to the tendency of atoms to gain a valence shell with a total of 8 electrons. Deduce the Lewis formula of molecules and ions for up to four electron pairs on each atom.